- Synthesis of enantiomeric diethyl (1R,2R)- and (1S,2R)-1,2,3- trihydroxypropylphosphonates
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Addition of diethyl phosphite to 2,3-O-cyclohexylidene-D-glyceraldehyde catalyzed by triethylamine or fluorides led to ca. 35:65 mixtures of diethyl (1R,2R)- and (1S,2R)-2,3-O-cyclohexytidene-1,2,3-trihydroxypropylphosphonates (4a) and (4b). Application of lithium diethylphosphonate only slightly improved diastereoselectivity. Through chromatographic separation of 4a and 4b the protected trihydroxypropylphosphonates became available for the first time as pure enantiomers. The 1S configuration in the major diastereoisomer 4b was assigned on the basis of conformational and configurational analysis of 1,2-O-isopropylidene derivatives obtained from the title compounds.
- Wroblewski, Andrzej E.,Balcerzak, Katarzyna B.
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Read Online
- Organocatalytic Michael addition to (D)-mannitol-derived enantiopure nitroalkenes: A valuable strategy for the synthesis of densely functionalized chiral molecules
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Carbohydrates are abundant renewable resources and are a feedstock for green chemistry and sustainable synthesis of the future. Among the hexoses and the pentoses present in biomass, mannitol was selected in the present project as a valuable platform, directly available from the chiral pool, to build highly functionalized molecules. Starting from (R)-2,3-O-cyclohexylidene glyceraldehyde, which is easily prepared in a large scale from D-mannitol, an enantiopure chiral nitro alkene was prepared by reaction with nitromethane, and its reactivity studied. Organocatalytic Michael addition of dimethyl malonate, β-keto esters, and other nucleophiles on the nitro alkene afforded high stereoselectivity and densely functionalized chiral molecules, which were further synthetically developed, leading to five-membered lactones and bicyclic lactams. Preliminary studies showed that the metal-free catalytic reaction on the chiral nitro alkene can be performed under continuous flow conditions, thus enabling the use of (micro)mesofluidic systems for the preparation of enantiomerically pure organic molecules from the chiral pool.
- Caruso, Lucia,Puglisi, Alessandra,Gillon, Emmerance,Benaglia, Maurizio
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Read Online
- An efficient synthesis of enantiomerically pure diethyl 2,3-dihydroxypropylphosphonate
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A reliable method for the synthesis of the enantiomerically pure diethyl (R)-2,3-dihydroxypropylphosphonate from 1,2;5,6-di-O-cyclohexylidene-D-mannitol is elaborated.
- Wroblewski, Andrzej E.,Halajewska-Wosik, Anetta
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Read Online
- Confirmation of the stereochemistry of two naturally occurring epimeric phenylpropanoids via synthesis: Elucidation of hitherto unknown full stereostructures
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Herein we report our efforts toward unequivocal assignment of the hitherto unknown absolute configurations of two naturally occurring phenylpropanoids from Abies delavayi and Abies fabri via a combination of chiral pool synthesis and single crystal X-ray
- Chakraborty, Ipsita,Chatterjee, Sandip,Manna, Avrajit,Bhaumik, Tanurima
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Read Online
- Novel 1,2,3-triazole-tethered Pam3CAG conjugates as potential TLR-2 agonistic vaccine adjuvants
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A focused library of water soluble 1,2,3-triazole tethered glycopeptide conjugates derived from variety of azido-monosaccharides and aliphatic azido-alcohols were synthesized through manipulation at the C-terminus of Pam3CAG and screened for their potential as TLR2 agonistic adjuvants against HBsAg antigen. In vitro ligand induced TLR2 signal activation was observed with all the analogues upon treatment with HEK blue TLR2 cell lines. Conjugate derived from ribose (6e), which exhibited pronounced HBsAg specific antibody (IgG) titer also shown enhanced CD8+ population indicating superior cell mediated immunity compared to standard adjuvant Pam3CSK4. Further, docking studies revealed ligand induced heterodimerization between TLR1 and 2. Overall, the result indicates the usefulness of novel conjugates as potential vaccine adjuvant.
- Mhamane, Tukaram B.,Sambyal, Shainy,Vemireddy, Sravanthi,Khan, Imran A.,Shafi, Syed,Halmuthur M., Sampath Kumar
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- A general and concise stereodivergent chiral pool approach toward trans-(4S,5R)- and cis-(4R,5R)-5-alkyl-4-methyl-γ-butyrolactones: Syntheses of (+)-trans- and (+)-cis-whisky and cognac lactones from D-(+)-mannitol
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A straightforward synthesis of (+)-trans-(4S,5R)- and (+)-cis-(4R,5R)-whisky lactones starting from D-(+)-mannitol has been reported here in fewer number of efficient steps compared to existing literature processes involving D-mannitol as the chiral pool starting material. Chiron approach directly translated chirality of D-mannitol to one of the two chiral centers in these target molecules. Toward this end, stereoisomerically pure trans- and cis-iodomethyl-γ-lactones were formed in the penultimate step. These two acted as versatile advanced common intermediates as they were also converted to the (+)-trans-(4S,5R)- and (+)-cis-(4R,5R)-cognac lactones, respectively. To the best of our knowledge, till date no synthesis of cognac lactones starting from D-mannitol has been reported. All these lactones are identified as the key aroma components of aged alcoholic beverages.
- Manna, Avrajit,Chakraborty, Ipsita,Chatterjee, Sandip,Bhaumik, Tanurima
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- Enantiodivergent syntheses of (+)- and (?)-1-(2,6-dimethylphenoxy)propan-2-ol: A way to access (+)- and (?)-mexiletine from D-(+)-mannitol
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Chiron approach was used to acquire optically pure (R)- and (S)-1-(2,6-dimethylphenoxy)propan-2-ol, immediate precursors of (S)- and (R)-mexiletines, respectively. Two different routes were followed from a D-mannitol-derived optically pure common precursor to get the enantiomeric alcohols separately. Comparison of their specific rotation values with the corresponding literature values as well as exact mirror-image relationship between their CD curves proved their high enantiopurity. These alcohols were then transformed to the corresponding amine-drugs in an efficient one-step process instead of two steps described in the literature.
- Manna, Avrajit,Chatterjee, Sandip,Chakraborty, Ipsita,Bhaumik, Tanurima
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- Synthesis of ABBV-168, a 2′-Bromouridine for the Treatment of Hepatitis C
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ABBV-168 is a dihalogenated nucleotide under investigation for the treatment of hepatitis C virus. Three synthetic routes aimed at achieving the stereoselective installation of the C2′ gem-Br,F substitution and subsequent Vorbruggen glycosylation were explored to prepare the penultimate nucleoside intermediate. Development culminated in a route to ABBV-168 featuring a de novo chromatography-free furanose synthesis, protecting group-directed Vorbruggen glycosylation, and highly selective phosphoramidation to furnish the API.
- Voight, Eric A.,Brown, Brian S.,Greszler, Stephen N.,Halvorsen, Geoff T.,Zhao, Gang,Kruger, Albert W.,Hartung, John,Lukin, Kirill A.,Martinez, Steven R.,Moschetta, Eric G.,Tudesco, Michael T.,Ide, Nathan D.
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p. 4723 - 4734
(2018/12/11)
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- Synthesis and in vitro biological evaluation of 3-amino-3-deoxydihydrosphingosines and their analogues
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The stereoselective synthesis of the 3-amino-3-deoxydihydrosphingosines and their isomeric analogues from dimethyl L-tartrate is described by means of [3,3]-sigmatropic rearrangements and the cross metathesis reaction as a cornerstone of the developed str
- Gonda, Jozef,Jáger, Dávid,Kuchár, Juraj,Martinková, Miroslava,Pilátová, Martina Bago,Raschmanová, Jana ?paková
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- Stereodivergent approach to Alzheimer's therapeutic agent (R)-(?) and (S)-(+)-arundic acid employing chiral 4-pentenol derivatives as building blocks
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An efficient stereodivergent total synthesis of anti-Alzheimer agent (R)-(?) and (S)-(+)-arundic acid has been achieved from both chiral and nonchiral materials. This strategy features an efficient approach to separable diastereomeric C-2 chiral 4-pentenol intermediates employing proline catalysed asymmetric α-aminooxylation and [3,3] sigmatropic Claisen rearrangement are the highlights of present synthesis.
- Bhosale, Viraj A.,Waghmode, Suresh B.
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p. 2342 - 2348
(2017/04/03)
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- Total Synthesis and Stereochemical Revision of 4,8-Dihydroxy-3,4-dihydrovernoniyne
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The first asymmetric total synthesis of two possible diastereomers (4S,5R)-4,8-dihydroxy-3,4-dihydrovernoniyne 5 and (4S,5S)-4,8-dihydroxy-3,4-dihydrovernoniyne 5a is accomplished. Salient features of the synthesis involve Cadiot-Chodkiewicz coupling and
- Kanikarapu, Suresh,Marumudi, Kanakaraju,Kunwar, Ajit C.,Yadav, Jhillu S.,Mohapatra, Debendra K.
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p. 4167 - 4170
(2017/08/23)
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- PROCESS FOR PREPARING AMINOTETRAHYDROPYRANS
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The present invention relates to a process for preparing 3-amino tetrahydropyrans and, more particularly, to an improved method for synthesizing a 2,3,5-substituted tetrahydropyran derivative, intermediate being used in the preparation of dipeptidyl pepti
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(2017/06/24)
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- (R)-2,3-cyclohexylideneglyceraldehyde, a chiral pool synthon for the synthesis of 2-azido-1,3-diols
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A new approach was proposed for the synthesis of 2-azido-1,3-diols from easily available and inexpensive chiral pool synthon (R)-2,3-O-cyclohexylidene-D-glyceraldehyde, through Mitsunobu azidation of 1,2-diols. Both C(2) and C(1) azides in variable ratios
- Rouf, Abdul,Aga, Mushtaq A.,Kumar, Brijesh,Taneja, Subhash C.
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p. 823 - 833
(2015/06/25)
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- A facile approach to chiral 1,4-benzodioxane toward the syntheses of doxazosin, prosympal, piperoxan, and dibozane
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The process describes the concise synthesis of (R/S)-enantiomers of doxazosin, an antidepressant drug and α-adrenergic receptor antagonists like prosympal, piperoxan, and dibozane in practical yields from easily available (R)-2,3-O-cyclohexylidene-d-glyce
- Rouf, Abdul,Aga, Mushtaq A.,Kumar, Brijesh,Taneja, Subhash Chandra
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p. 6420 - 6422
(2013/11/19)
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- Regioselective monochloro substitution in carbohydrates and non-sugar alcohols via Mitsunobu reaction: Applications in the synthesis of reboxetine
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A regioselective high yielding monochloro substitution (chlorohydrin formation) via Mitsunobu reaction is reported. In carbohydrates and sterically hindered non-sugars, only the primary hydroxyl group is chlorinated, whereas in the non-sugar 1,2- and 1,3-alcohols, predominantly the secondary chloride substitution occurs. The versatile methodology provides indirect access to epoxides with the retention of configuration, as against conventional Mitsunobu reaction which generates epoxides with inversion. The methodology was successfully used as a key step in the synthesis of optically active diastereoisomers of the antidepressant drug reboxetine from (R)-2,3-O- cyclohexylidene-d-glyceraldehyde in ～43% overall yields. The Royal Society of Chemistry.
- Dar, Abdul Rouf,Aga, Mushtaq A.,Kumar, Brijesh,Yousuf, Syed Khalid,Taneja, Subhash Chandra
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p. 6195 - 6207
(2013/09/12)
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- Trifluoroacetic anhydride promoted tandem conjugate addition of boronic acids/acetal ring opening
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A new stereoselective tandem reaction consisting of the metal-free conjugate addition of boronic acids followed by an intramolecular ring opening of a cyclic acetal has been disclosed. Optically pure polysubstituted tetrahydropyrans have been synthesized
- Roscales, Silvia,Csaky, Aurelio G.
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supporting information; experimental part
p. 1187 - 1189
(2012/04/17)
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- Novel isoxazolinyl spiropyrrolidinediones: 1,3-dipolar cycloaddition of 1-benzyl-3,3-dimethyl-5-methylenepyrrolidin-2,4-dione
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A simple and highly efficient methodology for the first synthesis of isoxazolinyl spiropyrrolidinedione starting from keto ester, is presented. Georg Thieme Verlag Stuttgart - New York.
- Bathich, Yaser,Syed Monudeen Khan, Sharifah Edayu Binti,Hamzah, Ahmad Sazali
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supporting information; experimental part
p. 1154 - 1156
(2011/07/09)
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- PREPARATION OF GEMCITABINE AND INTERMEDIATES THEREOF
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The present patent application relates to a process for the preparation gemcitabine or a salt thereof. More particularly it relates to preparation of 3,5- dihydroxy protected -2-deoxy-2,2-difluoro -1-oxoribose, an intermediate used in the preparation of gemcitabine and its salts by using cyclohexylidene or cyclopentylidene protecting group, with high yield and purity.
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(2010/05/14)
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- Synthesis of adamantylglycine using a diastereoselective grignard-to-nitrone addition
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In contrast to amino acids with a bulky substituent like tert-leucine, adamantylglycine has so far received little attention. Here, a new, practical synthesis of adamantylglycine is described. This is based on a highly diastereoselective addition of adamantyl Grignard reagent to 2,3-O-cyclohexylideneglyceraldehyde N-benzylnitrone, mediated by the Lewis acid diethylaluminum chloride. Adamantylglycine is obtained from the nitrone in 6 steps and 28% yield as a crystalline hydrochloride with 0.5 methanol incorporated.
- Baskakova, Alevtina,Frey, Wolfgang,Jaeger, Volker
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body text
p. 3693 - 3699
(2010/12/20)
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- Development of diastereoselective birch reduction-alkylation reactions of bi- and tricyclic β-alkoxy-α,β-unsaturated ketones
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(Chemical Equation Presented) Diastereoselective Birch reduction-alkylation reactions of bicyclic β-alkoxy-α,β-unsaturated carbonyl compounds and tricyclic analogues were investigated. Although the relative configuration of the product was altered accordi
- Hiroya, Kou,Ichihashi, Yusuke,Furutono, Ai,Inamoto, Kiyofumi,Sakamoto, Takao,Doi, Takayuki
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supporting information; experimental part
p. 6623 - 6630
(2009/12/31)
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- Synthetic studies on daphnicyclidin A: enantiocontrolled construction of the BCD ring system
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An enantiocontrolled entry to the tricyclic core of daphnicyclidin A with five chlral centers Including an all-carbon quaternary center Is reported. The synthesis features a highly dlastereoselectlve conjugate addition of nltromethane, an Ireland- Clalsen rearrangement, and a tandem acyliminium/ Mannich- type reaction.
- Ikeda, Shuhei,Shibuya, Masatoshi,Kanoh, Naoki,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 1833 - 1836
(2009/09/05)
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- Pyrogallol and its analogs can antagonize bacterial quorum sensing in Vibrio harveyi
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Bacteria can coordinate community-wide behaviors through quorum sensing, that is, the secretion and sensing of autoinducer (AI) molecules. Bacterial quorum sensing is implicated in the regulation of pathologically relevant events such as biofilm formation, bacterial virulence, and drug resistance. Inhibitors of bacterial quorum sensing could therefore be useful therapeutics. Herein we report for the first time the discovery of several pyrogallol compounds as single digit micromolar inhibitors of bacterial quorum sensing in Vibrio harveyi.
- Ni, Nanting,Choudhary, Gaurav,Li, Minyong,Wang, Binghe
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p. 1567 - 1572
(2008/09/21)
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- Enantioselective total synthesis of callipeltoside A: two approaches to the macrolactone fragment
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The enantioselective total synthesis of callipeltoside A is described. Two syntheses of the macrolactone subunit are included: the first relies upon an Ireland-Claisen rearrangement to generate the trisubstituted olefin geometry and the second utilizes an enantioselective vinylogous aldol reaction for this purpose. Enantioselective syntheses of the sugar and chlorocyclopropane side chain fragments are also disclosed. The relative and absolute stereochemistry of this natural product was determined by fragment coupling with the two enantiomers of the side chain fragment.
- Evans, David A.,Burch, Jason D.,Hu, Essa,Jaeschke, Georg
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p. 4671 - 4699
(2008/09/21)
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- Synthetic strategies to epoxydiynes and a key synthon of the neocarzinostatin chromophore
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We present herein our recent efforts towards the synthesis of epoxydiynes which represent an unusual structural feature of the neocarzinostatin chromophore. A number of different routes to these epoxydiynes have been explored with varying success. Ultimately a concise and convergent approach was developed, which involved the addition of an allenyl zinc bromide to propargylic ketones/aldehydes followed by epoxide formation. This new protocol enabled us to synthesise a fully elaborated epoxydiyne which will find application for our studies towards the total synthesis of the NCS chromophore. The Royal Society of Chemistry.
- Thominet, Olivier,Baker, James R.,Britton, Hugh,Etheridge, Zac C.,Soscia, Marco G.,Caddick, Stephen
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p. 3703 - 3712
(2008/09/21)
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- EXPEDITIOUS SYNTHESIS OF DPD
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This invention provides a practical synthesis route for 4,5-dihydroxypentane-2,3-dione (DPD), an unstable small molecule which is proposed to be the source of universal signaling agents for quorum sensing in bacteria. The synthesis route includes new intermediates and allows preparation of isotopically-labeled DPD and ent-DPD. The method provides sufficient quantities of DPD for study of spontaneous binding of borate to DPD, the signal for the marine bacteria V. harveyi
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(2008/06/13)
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- First stereoselective syntheses of (-)-siphonodiol and (-)- tetrahydrosiphonodiol, bioactive polyacetylenes from marine sponges
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The first stereoselective total syntheses of the bioactive marine polyacetylenes (-)-siphonodiol and (-)-tetrahydrosiphonodiol were achieved using highly convergent approaches based on optimized Cadiot-Chodkiewicz and sequential Sonogashira cross-coupling reactions.
- Lopez, Susana,Fernandez-Trillo, Francisco,Midon, Pilar,Castedo, Luis,Saa, Carlos
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p. 6346 - 6352
(2007/10/03)
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- An expeditious synthesis of DPD and boron binding studies
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(Chemical Equation Presented) A practical synthesis has been developed for DPD (4,5-dihydroxypentane-2,3-dione), an unstable small molecule that is proposed to be the source of universal signaling agents for quorum sensing in bacteria. The synthesis allows preparation of isotopically labeled DPD and ent-DPD as well as detailed studies of spontaneous binding to borate to give the unusual borate complex 6, the signal for marine bacteria such as Vibrio harveyi.
- Semmelhack, Martin F.,Campagna, Shawn R.,Federle, Michael J.,Bassler, Bonnie L.
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p. 569 - 572
(2007/10/03)
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- ANALOGS OF LYSOPHOSPHATIDIC ACID AND METHODS OF MAKING AND USING THEREOF
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Described herein are analogs of lysophosphatidic acid. Also described herein are methods of making and using analogs of lysophosphatidic acid.
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- Enantiomeric synthesis of the SPIKET-P enantiomers
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A convenient synthesis of the antipodes of the title compound has been developed starting from (R)-1,2,5,6-dicyclohexylidene mannitol. Some of the key features of the syntheses were simple reaction protocols, and stereoselective inversion of chiral 1,2-diol moiety via neighbouring group assisted acetylation.
- Sharma, Anubha,Iyer, Prema,Gamre, Sunita,Chattopadhyay, Subrata
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p. 1037 - 1040
(2007/10/03)
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- An Improved Methodology for the Synthesis of Enantiomerically Pure (S)-2,3-O-Cyclohexylideneglyceraldehyde
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An improved methodology to prepare (S)-2,3-O-cyclohexylideneglyceraldehdye is described. Starting from the commercially available (L)-cyclohexylidene protected ascorbic acid the enantiomerically pure aldehyde was synthesized inonly two steps in 41 percent overall yield. 5,6-O-cyclohexylidene-(L)-ascorbic acid -> (S)-2,3-O-cyclohexylideneglyceraldehyde
- Benaglia, M.,Caporale, M.,Puglisi, A.
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p. 383 - 386
(2007/10/03)
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- On the selectivity of oxynitrilases towards α-oxygenated aldehydes
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Different α-alkoxy and α,β-di-alkoxy substituted aldehydes have been submitted to the catalytic action of the oxynitrilases from almond (PaHNL) or from Hevea brasiliensis (HbHNL), in order to explore the possibility of using these enzymes for the preparation of complex cyanohydrins. The selectivity of both enzymes towards these compounds was found to be largely dependent on the substitutents, being low with the aldehydes carrying the sterically more demanding phenyl substituent. Contrary to the chemical addition of HCN, which always occurs with a slight preference for the formation of the anti diastereoisomers, the enzymatic cyanuration - occurring with a facial preference, Si or Re according to the biocatalyst used - gave a mixture of cyanohydrins that, depending on the starting enantiomeric aldehyde, can be enriched in the syn diastereoisomers.
- Bianchi, Paola,Roda, Gabriella,Riva, Sergio,Danieli, Bruno,Zabelinskaja-Mackova, Antonina,Griengl, Herfried
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p. 2213 - 2220
(2007/10/03)
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- Asymmetric synthesis of the chlorocyclopropane-containing callipeltoside A side chain.
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[reaction: see text] The callipeltoside A chlorocyclopropyl-containing dienyne side chain has been synthesized in nine steps and 33% overall yield from commercially available 1,2,5,6-O-dicyclohexylidene-D-mannitol. The key steps in the synthesis are a hig
- Evans,Burch
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p. 503 - 505
(2007/10/03)
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- Stereoselective synthesis of syn-α-methyl-β-hydroxy esters
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Boron enolates of an ethyl ketone structurally related to erythrulose react with achiral aldehydes in a highly stereoselective fashion to yield 1,2-syn/1,3-syn stereoisomers. Oxidative cleavage of the aldol adducts yields enantiopure O-formylated syn-α-me
- Carda, Miguel,Murga, Juan,Falomir, Eva,Gonzalez, Florenci,Marco, J. Alberto
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p. 3211 - 3220
(2007/10/03)
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- Acylnitrene route to vicinal amino alcohols. Application to the synthesis of (-)-bestatin and analogues
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Bestatin, valinoctin A, and microginin are naturally occurring small peptides containing a nonproteinogenic α-hydroxy-α-amino acid at the N-terminus of the peptide chain. We report here our development of a general method for the synthesis of α-hydroxy-β-amino acids and exemplify this with a synthesis of (-)-bestatin and analogues. Our synthesis utilizes an intramolecular acylnitrene-mediated aziridination to generate a key bicyclic aziridine in excellent yield and stereoselectivity. This bicyclic aziridine can be opened with a number of organometallic reagents to provide a series of substituted oxazolidinones. The oxazolidinones are readily converted to bestatin and a series of bestatin analogues. As part of this approach, we have developed a new method for the synthesis of azidoformates. We have also demonstrated that oxazolidinones can be selectively hydrolyzed in the presence of peptide bonds. This acylnitrene route to bestatin should prove useful for the synthesis of a variety of analogues of bestatin as well as other α-hydroxy-β-amino acids and their corresponding peptides.
- Bergmeier, Stephen C.,Stanchina, Dionne M.
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p. 2852 - 2859
(2007/10/03)
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- Enantioselective Synthesis and Absolute Configuration of (R)-(+)-Lunacridine and (S)-(+)-Lunacrine
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(R)-(-)-Lunacridine 1 has been synthesized in 97.3percent e.e. using a chiron approach through L-valine and D-mannitol as the starting compounds to corroborate its absolute configuration.The key intermediate (S)-1,2-epoxy-3-methylbutane 11 was synthesized from (L)-valine (3 -> -> 11) and a (D)-mannitol derivative (12 -> -> 11) via functional group manipulation.The epoxide 11 was reacted with lithiated 2,4,8-trimethoxyquinoline 17 and the resulting product 18 was selectively deprotected at the 2-position followed by N-methylation of 19 to give 1.In an alternative strategy 11 was transformed into the THP-acid 23 through the chiral lactone 20.Condensation of 23 with substituted methyl anthranilate gave the amide 24 which on cyclisation, methylation and deprotection steps sequentially afforded 1.
- Anand, Ramesh C.,Selvapalam, N.
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p. 126 - 142
(2007/10/03)
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- (R)-2,3-O-Cyclohexylideneglyceraldehyde, a Versatile Intermediate for Asymmetric Synthesis of Chiral Alcohol
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Grignard addition to (R)-2,3-O-cyclohexylideneglyceraldehyde (IIa) gave rise to column chromatographically separable diastereo alcohols 2 and 3 including highly functionalized and synthetically exploitable homoallylic alcohols 2e and 3e and homopropargyli
- Chattopadhyay, A.,Mamdapur, V. R.
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p. 585 - 587
(2007/10/02)
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- Total Synthesis of Symbioramide, a Novel Ca(2+)-ATPase Activator from Symbiodinium sp.
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The first total synthesis of symbioramide 1 has been accomplished by the coupling of D-erythro-dihydrosphingosine with an unusual, chiral α-hydroxy-β,γ-unsaturated fatty acid prepared from L-ascorbic acid, and simultaneously established the complete stereostructure of 1 to be (2S,2'R,3R,3'E)-N-(2'-hydroxyoctadec-3'-enoyl)dihydrosphingosine.
- Yoshida, Jun,Nakagawa, Masako,Seki, Hiroko,Hino, Tohru
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p. 343 - 350
(2007/10/02)
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- First Total Synthesis of Symbioramide, a Novel Ca2+-ATPase Activator from Symbiodinium sp.
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The first total synthesis of symbioramide (1) is described and simultaneously established the complete stereostructure of 1 to be (2S,3R,2'R,3'E)-N-(2'-hydroxy-3'-octadecenoyl)-dihydrosphingosine.
- Nakagawa, Masako,Yoshida, Jun,Hino, Tohru
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p. 1407 - 1410
(2007/10/02)
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- 3-Alkylated (R)-2,3-Dihydroxyalkyl p-Toluenesulfonates - Homochiral Building Blocks for Modified Steroid Side Chains
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Oxidative cleavage of 1,2:5,6-di-O-cyclohexylidene-D-mannitol (2) with lead(IV) acetate yields (R)-2,3-O-cyclohexylideneglyceraldehyde, which was transformed by oxidation and esterification into methyl 2,3-O-cyclohexylideneglycerate.Grignard reaction with
- Schroetter, Eberhard,Luong, Tran Thanh,Schick, Hans
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p. 191 - 197
(2007/10/02)
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- Asymmetric Syntheses via Heterocyclic Intermediates, XXVII. - Reactions of Metallated Bislactim Ethers of cyclo(-L-Val-Gly-) with (R)- and (S)-Glyceraldehyde and with (S)-Lactaldehyde
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The titanium derivative 3 and the lithium derivative 2 of the bislactim ether 1 of cyclo(-L-Val-Gly-) react with (R)- and (S)-glyceraldehyde (cyclohexylidene-protected, 9) and with (S)-lactaldehyde (Mem-protected, 10) to give virtually only one diastereomer.The extent of asymmetric induction is higher for (S)-9 and 10 than for (R)-9.The results can be rationalized on the basis of pericyclic reactions with six-membered chair-like transition states. - On acid hydrolysis (subsequent to O-acetylation) the aldol-type addition products 11, 12, and 13 are cleaved to give theamino acid methyl esters 14, 15, and 16 with multiple stereocenters. 15 and 16 are enantiomerically and diastereomerically pure.
- Grauert, Matthias,Schoellkopf, Ulrich
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p. 1817 - 1824
(2007/10/02)
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- Facile Synthesis of 1,2:5,6-Di-O-cyclohexylidene-D-mannitol and 2,3-O-Cyclohexylidene-D-glyceraldehyde
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The reaction of cyclohexanone diethyl acetal with D-mannitol yielded quantitatively 1,2:5,6-di-O-cyclohexylidene-D-mannitol (1) and its isomer (2).From 1, 2,3-O-cyclohexylidene-D-glyceraldehyde (3) was obtained in a quantitative yield without racemization.
- Sugiyama, Takeyoshi,Sugawara, Hidehiko,Watanabe, Masashi,Yamashita, Kyohei
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p. 1841 - 1844
(2007/10/02)
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