- Hydromagnesiation of 3-Trimethylsilylprop-2-yn-1-ol. A Simple Route to (E)-3-Trimethylsilylalk-2-en-1-ols
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Hydromagnesiation of 3-trimethylsilylprop-2-yn-1-ol affords the alkenylmagnesium halide (3) exclusively, which is valuable as a precursor of various (E)-3-trimethylsilylalk-2-en-1-ols.
- Sato, Fumie,Watanabe, Hiroshi,Tanaka, Youichi,Sato, Masao
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Read Online
- Ambruticins: tetrahydropyran ring formation and total synthesis
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The ambruticins are a family of polyketide natural products which exhibit potent antifungal activity. Gene knockout experiments are in accord with the proposal that the tetrahydropyran ring of the ambruticins is formedviathe AmbJ catalysed epoxidation of the unsaturated 3,5-dihydroxy acid, ambruticin J, followed by regioselective cyclisation to ambruticin F. Herein, a convergent approach to the total synthesis of ambruticin J is described as well as model studies involving epoxidation and cyclisations of unsaturated hydroxy esters to give tetrahydropyrans and tetrahydrofurans. The total synthesis involves preparation of three key fragments which were unitedviaa Suzuki-Miyaura cross-coupling and Julia-Kocienski olefination to generate the required carbon framework. Global deprotection to a triol and selective oxidation of the primary alcohol gave, after hydrolysis of the lactone, ambruticin J.
- Bowen, James I.,Crump, Matthew P.,Wang, Luoyi,Willis, Christine L.
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supporting information
p. 6210 - 6215
(2021/07/28)
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- Synthesis of multinuclear Rh(I) complexes bearing triazolylidenes and their application in C-C and c-Si bond forming reactions
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Multidentate carbene ligands are valuable frameworks for the preparation of carbene complexes displaying higher nuclearity. In the present work, we report the synthesis of a series of mono- to tetra-[Rh(COD)I] complexes (3a- d) supported by mesoionic triazol-5-ylidenes. The general synthetic procedure involves the one step reaction of the appropriate triazolium (2a-d) salt in the presence of KHMDS and stoiquiometric amounts of the rhodium(I) precursor. Treatment of complexes 3a-d with an excess of carbon monoxide allows for the quantitative preparation of complexes 4a-d featuring a [Rh(CO)2I] fragment used for the detemination of the donor properties of the new triazolylidene ligands. All complexes have been fully characterized by means of 1H and 13C NMR spectroscopy, melting point, elemental analysis, and in the case of complex 3a, by X-ray crystallography. Comparison of the catalytic activity of the new rhodium complexes in C-C and C-Si bond forming processes demonstrate the enhanced performance of the tetranuclear species suggesting the possibility of strong cooperative effects in these multinuclear complexes.
- Mendoza-Espinosa, Daniel,Rendón-Nava, David,Vásquez-Pérez, Jose M.,Sandoval-Chávez, Cesar I.,Alvarez-Hernández, Alejandro
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p. 3961 - 3971
(2020/12/01)
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- Exploring the scope of tandem palladium and isothiourea relay catalysis for the synthesis of α-amino acid derivatives
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The scope and limitations of a tandem N-allylation/[2,3]-rearrangement protocol are investigated through the incorporation of a variety of functional groups within an allylic phosphate precursor. This method uses readily accessible N,N-dimethylglycine aryl esters and functionalized allylic phosphates, forming quaternary ammonium salts in situ in the presence of a palladium catalyst. Subsequent enantioselective [2,3]-sigmatropic rearrangement, promoted by the chiral isothiourea tetramisole, generates α-amino acid derivatives with two contiguous stereocenters. The incorporation of electron-withdrawing ester and amide groups gave the best results, furnishing the desired products in moderate to good yields (29-70percent), with low diastereocontrol (typically 60:40 dr) but high enantioselectivity (up to 90:10 er). These results indicate that substrate-catalyst interactions in the proposed transition state are sensitive to the substitution pattern of the substrates.
- Bitai, Jacqueline,Slawin, Alexandra M.Z.,Cordes, David B.,Smith, Andrew D.
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supporting information
(2020/07/27)
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- An Aliphatic Bischler-Napieralski Reaction: Dihydropyridones by Cyclocarbonylation of 3-Allylimidazolidin-4-ones
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The N-chloroformylimidazolidinone derivative of enantiopure l-alanine was deprotonated to form an enolate and functionalized with a series of allylic halides. Treatment of the resulting carbamoyl chlorides with potassium iodide led to cyclization of the allylic substituent onto the carbonyl group in an intramolecular aliphatic Friedel-Crafts-type acylation that corresponds to an aliphatic Bischler-Napieralski reaction. The product 3,4-dihydropyridinones were amenable to further functionalization, and finally hydrolysis, to deliver a series of enantio-enriched pipecolic acid derivatives.
- Amer, Mostafa M.,Olaizola, Olatz,Carter, Jennifer,Abas, Hossay,Clayden, Jonathan
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supporting information
p. 253 - 256
(2020/01/02)
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- Nickel-Catalyzed Direct Coupling of Allylic Alcohols with Organoboron Reagents
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The direct coupling of allylic alcohols with arylboronic acids or their derivatives catalyzed by Ni(cod)2 in the presence of a catalytic amount of base has been developed. A wide variety of allylic substrates or arylboronic acids turned out to be applicable to this catalytic system. The present method does not require the use of ligands for stabilizing the nickel catalyst in most cases or additional activators for activation of allylic alcohols.
- Wang, Gaonan,Gan, Yi,Liu, Yuanhong
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p. 916 - 920
(2018/09/22)
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- Si-directed regiocontrol in asymmetric Pd-catalyzed allylic alkylations using C1-ammonium enolate nucleophiles
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Cooperative catalysis enables the direct enantioselective α-allylation of linear prochiral esters using Si-substituted allyl electrophiles. The Si-substituent directs the regioselectivity of enantioselective bond formation and provides products containing synthetically versatile pentafluorophenyl ester and vinylsilane moieties. Critical to the efficacy of this process was the recognition that the ancillary ligand on palladium could be altered to prevent formation of a deleterious ether by-product, whilst retaining enantioselectivity through the Lewis base catalyst. Flexibility such as this is unique to cooperative catalysis events and provides efficient access to an array of enantioenriched products that are orthogonally functionalized and easily modified.
- Fyfe, James W.B.,Kabia, Omaru M.,Pearson, Colin M.,Snaddon, Thomas N.
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supporting information
p. 5383 - 5391
(2018/04/23)
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- Synthesis method of methylcyclopropene probe
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The invention discloses a synthesis method of a methylcyclopropene probe, and belongs to the technical field of small organic molecule fluorescent probes. The method includes the steps that 3-(trimethylsilyl)-2-propyn-1-ol serves as the raw material and i
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Paragraph 0019-0020
(2017/04/05)
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- Asymmetric synthesis of 12-hydroxyheptadecatrienoic acid and its 5,6-dihydro- and 14,15-dehydro-derivatives
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Natural 12-hydroxyheptadecatrienoic acid (12-HHT) with an S configuration was synthesised by a Suzuki-Miyaura coupling of C10-C17 iodo alcohol with C1-C9 vinylborane. The iodo alcohol was synthesised by utilising Sharpless asymmetric epoxidation of the corresponding trimethylsilyl alcohol. The method yielded more than 100 mg of 12-HHT. Similarly, syntheses of 5,6-dihydro- and 14,15-dehydro derivatives of 12-HHT, known as HHD and HHTE, respectively, were completed in a stereoselective manner.
- Kobayashi, Yuichi,Morita, Masao,Ogawa, Narihito,Kondo, Daiki,Tojo, Toshifumi
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supporting information
p. 10667 - 10673
(2016/11/30)
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- A new protocol for nickel-catalysed regio- and stereoselective hydrocyanation of allenes
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Regio- and stereoselective hydrocyanation under nickel catalysis is described. This report shows that allenyl C-C double bonds are discriminated and converted to the corresponding carbonitriles as a single product. The key functionalities for achieving high regio- and stereocontrol are aryl and cyclopropyl groups in the substrates. This journal is
- Arai, Shigeru,Hori, Hiroto,Amako, Yuka,Nishida, Atsushi
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supporting information
p. 7493 - 7496
(2015/05/04)
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- Design and synthesis of potent macrocyclic HIV-1 protease inhibitors involving P1-P2 ligands
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A series of potent macrocyclic HIV-1 protease inhibitors have been designed and synthesized. The compounds incorporated 16- to 19-membered macrocyclic rings between a nelfinavir-like P2 ligand and a tyrosine side chain containing a hydroxyethylamine sulfonamide isostere. All cyclic inhibitors are more potent than their corresponding acyclic counterparts. Saturated derivatives showed slight reduction of potency compared to the respective unsaturated derivatives. Compound 8a containing a 16-membered ring as the P1-P2 ligand showed the most potent enzyme inhibitory and antiviral activity. This journal is the Partner Organisations 2014.
- Ghosh, Arun K.,Schiltz, Gary E.,Rusere, Linah N.,Osswald, Heather L.,Walters, D. Eric,Amano, Masayuki,Mitsuya, Hiroaki
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p. 6842 - 6854
(2014/10/15)
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- Studies on retro-[1,4] Brook rearrangement of 3-silyl allyloxysilanes. Observation of the formation of unusual 3,3-bissilyl enols
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Detailed investigations of the retro-[1,4] Brook rearrangement of 3-silyl allyloxysilanes are described. Based on control experiments and NMR studies, rationalizations are proposed for the formation of 3,3-bissilyl enols, unusual compounds that are stable
- Gan, Zubao,Wu, Ya,Gao, Lu,Sun, Xianwei,Lei, Jian,Song, Zhenlei,Li, Linjie
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supporting information; experimental part
p. 6928 - 6934
(2012/08/29)
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- Expedient access to branched allylic silanes by copper-catalysed allylic substitution of linear allylic halides
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An unprecedented copper-catalysed allylic transposition enables the regioselective synthesis of branched allylic silanes from linear allylic halides through direct C-Si bond formation.
- Vyas, Devendra J.,Oestreich, Martin
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supporting information; experimental part
p. 568 - 570
(2010/05/01)
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- Fluorination process
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Compounds of formula (II), (IIIa) or (IIIb) (variables are described in the specification) are prepared by fluorination of β,γ-unsaturated alkyl silanes. These compounds are useful as building blocks in the pharmaceutical industry.
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Page/Page column 26
(2008/06/13)
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- Formal synthesis of tubelactomicins via a transannular Diels-Alder approach
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A formal synthesis of the antimicrobial tricyclic macrolides, tubelactomicins A and E, featured by a transannular Diels-Alder (TADA) approach, has been explored. The key issue for the transannular cyclization was the synthesis of a 24-membered macrolacton
- Anzo, Toshimi,Suzuki, Akari,Sawamura, Kiyoto,Motozaki, Toru,Hatta, Madoka,Takao, Ken-ichi,Tadano, Kin-ichi
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p. 8442 - 8448
(2008/03/13)
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- Enantioselective synthesis of allylsilanes bearing tertiary and quaternary si-substituted carbons through Cu-catalyzed allylic alkylations with alkylzinc and arylzinc reagents
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All sorts of allylsilanes including, for the first time, those that contain a Si-bonded quaternary carbon, were synthesized through efficient and highly enantioselective Cu-catalyzed asymmetric allylic alkylations. Reactions may involve dialkyl- as well as diarylzinc reagents and are promoted by various chiral N-heterocyclic carbene complexes.
- Kacprzynski, Monica A.,May, Tricia L.,Kazane, Stephanie A.,Hoveyda, Amir H.
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p. 4554 - 4558
(2008/09/17)
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- Formal enantioselective synthesis of (+)-compactin
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The challenging structural features and important biological activity of (+)-compactin (1) explain the substantial synthetic interest that it has generated. We report a novel enantioselective approach to the advanced intermediate 2a, which constitutes a formal synthesis of (+)-1. The sequence utilizes MacMillan's organocatalytic Mukaiyama-Michael reaction, which stereoselectively adds the silyloxyfuran 6 to α,β-unsaturated aldehyde 7. The chirality generated in this reaction guides the formation of the other three consecutive stereocenters found in 2a.
- Robichaud, Joel,Tremblay, Francois
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p. 597 - 600
(2007/10/03)
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- Allylsilane-modified amino acids from the Claisen rearrangement
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The Claisen rearrangement of the N-protected, silylated allyl glycinates 11 and 12 led to the formation of allyl/silyl-functionalized amino acids 13 and 14 in yields up to 80%. The diastereoisomer ratio varied from 2:1 to 29:1 for 11mb, and from 2:1 to 46:1 (syn/anti) for 12mb, depending on reaction conditions, as shown by X-ray crystallographic analysis of 14mb. The relationship between the size of the alkyl groups on the chlorosilane reagent (Me2R″SiCl, R″ = Cl, Me, t-Bu, Ph) used as an enolate trap and the observed stereoselectivity was investigated in the case of the Ireland - Claisen variant. Me3SiCl gave the best results. However, the size of the alkyl groups on the silylated ester (Me2R″Si, R = Me, t-Bu, Ph, i-Pr) did not exert a significant effect on the diastereoselectivity or yield of the rearrangement.
- Mohamed, Mustafa,Brook, Michael A.
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p. 4165 - 4181
(2007/10/03)
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- The regioselectivity of 1,3-disubstituted allylmetal species towards electrophiles: 1-(Trimethylsilyl)alk-2-enylpotassium compounds
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1-(Trimethylsilyl)alk-2-enylpotassium species are readily generated by deprotonation of (alk-2-enyl)trimethylsilanes with the superbasic mixture of butyllithium and potassium tert-butoxide. Like the parent compound 1- (trimethylsilyl)allylpotassium, they too react with a variety of electrophiles preferentially, if not exclusively, at the silyl-distant terminus of the allyl moiety, thus producing branched enesilanes. The opposite regioselectivity previously observed with iodomethane hence appears to be an exception.
- Schlosser, Manfred,Franzini, Livia
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p. 707 - 709
(2007/10/03)
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- A concise synthesis of (+)-cerulenin from a chiral oxiranyllithium
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(+)-Cerulenin, a potent fungal inactivator of fatty acid synthases, has been prepared in optically pure form by a sequence involving reaction of a chiral oxiranyllithium with (4E,7E)-nonadienal. Synthesis of the former takes advantage of a particularly favorable Sharpless epoxidation and metalation to a configurationally stable organolithium, while the latter is available in quantity by a direct and improved route.
- Mani, Neelakandha S.,Townsend, Craig A.
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p. 636 - 640
(2007/10/03)
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- Anti-hydroalumination of homo- and bishomopropargyl alcohols
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The reaction of ω-Me3Si- or ω-Me3Ge-substituted 3-butyn-1-ol, 4-pentyn-1-ol, and their derivatives with DIBAL-H and a small trialkylalane, e.g., Me3Al or Et3Al, at 23°C gives, after iodinolysis, the corresponding (Z)-4-iodo-3-buten-1-ols and (Z)-5-iodo-4-penten-1-ols in a highly stereo- and regio-selective manner, most probably via endo-dig mode cyclic anti-hydroalumination, while treatment of ω-carbosubstituted 3-butyn-1-ols with Red-Al or LialH4 at high temperatures followed by iodinolysis can give the corresponding (Z)-4-iodo-3-buten-1-ols also in a highly regio- and stereoselective manner.
- Ma, Shengming,Liu, Fang,Negishi, Ei-Ichi
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p. 3829 - 3832
(2007/10/03)
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- N-derivatives of 1-deoxy nojirimycin
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This invention relates to novel N-derivatives of 1-deoxy nojirimycin, to the method for their preparation and to their use in the treatment of diabetes and the use against retro-viruses, particularly in the treatment of acquired immuno-deficiency syndrome
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- Stereocontrolled synthesis of α-trialkylsilyl-β,γ-unsaturated aldehydes via palladium (0) catalysis synthetic usefulness
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The reaction of silicon substituted vinyloxiranes in the presence of catalytic amount of palladium (0) catalyst affords the title compounds. This new reaction proceeds smoothly, under very mild conditions and with complete chirality transfer. One-pot addition of selected organometallic nucleophiles to these aldehydes at very low temperature led to a highly selective preparation of the corresponding alcohols in very good yields. Influence of substituents on the silicon atom and of the ligands of palladium have been studied.
- Le Bideau,Gilloir,Nilsson,Aubert,Malacria
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p. 7487 - 7510
(2007/10/03)
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- Stereoselective synthesis of heterocyclic zinc reagents via a nickel-catalyzed radical cyclization
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Unsaturated iodo or bromo acetals of type 2 undergo a smooth cyclization mediated by diethylzinc (2 equiv) and Ni(acac)2 as catalyst (2-5 mol %). These cyclizations proceed via a radical mechanism affording a (tetrahydrofuranylmethyl)zinc halide of type 1, which can be reacted with various electrophiles after a transmetalation with CuCN·2LiCl. High stereoselectivities are usually observed in the ring closures, especially if monocyclic cyclization precursors are used. In these cases, bicyclic products of the endo-configuration are obtained with over 94% diastereoselectivity. The synthetic method has been extended to the preparation of a nitrogen heterocycle and over 98% pure trans-4,5-disubstituted γ-butyrolactones. A short enantioselective synthesis of (-)-methylenolactocine (3) using the radical cyclization and a novel oxidation of α-silyl zinc peroxide as a key step is also described.
- Vaupel, Andrea,Knochel, Paul
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p. 5743 - 5753
(2007/10/03)
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- N-derivatives of 1-deoxy nojirimycin
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This invention relates to novel N-derivatives of 1-deoxy nojirimycin, to the method for their preparation and to their use in the treatment of diabetes and the use against retro-viruses, particularly in the treatment of acquired immuno-deficiency syndrome
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- A New Iterative Route to Optically Active Polyols Using α-Alkoxy Silanes as Key Intermediates
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A new iterative and modular strategy which is applicable to the synthesis of any enantiomers and diastereomers of straight chain 1,n-polyols has been developed utilizing electrochemical oxidation of α-alkoxy silanes.
- Yoshida, Jun-ichi,Maekawa, Tsuyoshi,Morita, Yuko,Isoe, Sachihiko
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p. 1321 - 1322
(2007/10/02)
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- Silicon-Mediated Skipped Diene Synthesis. Application to the Melon Fly Pheromone
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The 1,4-diene unit is a key structural feature of many fatty acid derived natural products including arachidonic acid, several of the leukotrienes, and a variety of insect pheromones.In this paper substituted cyclopropyl>carbinols are demonstrated to cleave redily, upon treatment with acid or upon conversion to the corresponding mesylates, to give mono- and disubstituted 1,4-pentadienes.Stereoselective formation of cis and trans olefins from diastereomeric carbinols has been examined.Control of configuration at the olefin derived from the trimethylsilyl-bearing terminus of the cyclopropane system was found to be only moderate while the olefin derived from the carbinol terminus of the cyclopropane system was produced with high trans stereoselectivity.From these results it is concluded that the cleavage of the cyclopropane ring is neither significantly accelerated by, nor strongly coupled to, cleavage of the carbon-silicon bond.The high stereoselectivity observed for the formation of the trans configuration at the olefin derived from the carbinol terminus has been applied to the synthesis of a constituent of the melon fly pheromone.
- Wilson, Stephen R.,Zucker, Paul A.
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p. 4682 - 4693
(2007/10/02)
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- Cyclic Olefins by Anodic Oxidation of β-(Trimethylsilyl)carboxylic Acids. - β-(Trimethylsilyl)acrylic Acid Derivatives as Acetylene Equivalents in Diels-Alder Reactions
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Trimethylsilyl-substituted dienophiles 1, 2, and 4 react with dienes 6-14 in 66-100percent yields to give β-trimethylsilyl-substituted carboxylic acids 15-25, some of which are hydrogenated to 26-31.These are decarboxylated-desilylated to cyclic olefins 35-47 by Non-Kolbe electrolysis in 45-91percent yields.The dienophiles 1, 2, and 4 are thus suitable acetylene equivalents for Diels-Alder reactions.
- Hermeling, Dieter,Schaefer, Hans J.
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p. 1151 - 1158
(2007/10/02)
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- TRANSITION-METAL CATALYZED SILYLZINCATION AND SILYLALUMINATION OF ACETYLENIC COMPOUNDS
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Dialkyl(dimethylphenylsilyl)zinclithium and trialkyl(dimethylphenylsilyl)aluminiumlithium add effectively to internal acetylenes as well as terminal ones in the presence of transition-metal catalysts to provide vinylsilanes with high stereo- and regiosele
- Wakamatsu, Kuni,Nonaka, Tsuyoshi,Okuda, Yasuhiro,Tueckmantel, Werner,Oshima, Koichiro,et al.
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p. 4427 - 4436
(2007/10/02)
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- REGIOSELECTIVE SYNTHESIS OF (+/-)-GABACULINE
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(+/-)-Gabaculine has been synthesized via an intramolecular reaction of an N-acyliminium intermediate with a propargyl silane, followed by allene ozonolysis and a Shapiro reaction.
- Hiemstra, Henk,Klaver, Wim J.,Speckamp, W. Nico
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p. 1411 - 1414
(2007/10/02)
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- Carbolithiations of 3-(trimethylsilyl)-2-propyn-1-ols
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Alkyllithiums undergo trans addition to-3-(trimethylsilyl)-2-propyn-1-ols to yield (1-lithiovinyl)silanes.Due to unidentified side-reactions, yield do not exceed 20 percent.
- Kruithof, K. J. H.,Schmitz, R. F.,Klumpp, G. W.
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- THE SYNTHESIS OF E-(2S,3S)-3-TRIMETHYLSILYLGLYCIDOL AND ITS CONVERSION TO (-)-PROPRANOLOL
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(-)-Propranolol was synthesized in a highly enantio- and regioselective manner by using titanium mediated asymmetric epoxidation via the key intermediate, E-(2S,3S)-3-trimethylsilylglycidol.
- Katsuki, Tsutomu
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p. 2821 - 2822
(2007/10/02)
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- 1-LITHIO-1-BENZENESULFINYL-2-TRIMETHYLSILYLETHANE AS A 2-TRIMETHYLSILYLVINYL ANION EQUIVALENT IN REACTIONS WITH ALHEDYDES, KETONES AND EPOXIDES
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Aldehydes, ketones and epoxides give adducts with 1-lithio-1-benzenesulfinyl-2-trimethylsilylethane which upon neutralization eliminate benezenesulfenic acid efficiently at 76 deg C to yield trans-3-(trimethylsilyl)allyl alcohols and trans-4-(trimethylsilyl)-3-alken-1-ols.
- Hsiao, C-N.,Shechter, H.
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p. 2371 - 2374
(2007/10/02)
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- Silylalkenes and -dienes via (Silylalkylidene)phosphoranes
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The reaction of the (silylalkylidene)phosphoranes 3 and 4 with the ketones 5 - 7 and 16 leads to the silylated olefins 8 - 10 and 17, 18.With fluorenone (11), 3 affords the spiro compound 14, via (silylpropylidene)fluorene 13, which is also obtained by dehydration of 9--9-fluorenol (12).With the ketones 5 - 7 and 11, triphenylphosphorane (20) yields the silylated dienes 21 - 24.From cyclohexane (22) and tetracyanoethene (25) the spiran 26 is formed by cycloaddition.
- Birkofer, Leonard,Kittler, Juergen
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p. 3737 - 3746
(2007/10/02)
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- SYN-ADDITION VON TRIS(TRIMETHYLSILYL)ALUMINIUM AN ALKINE: EINE NEUE SYNTHESE FUER VINYLSILANE
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A new method for the synthesis of vinylsilanes by syn-addition of tris(trimethylsilyl)aluminium to alkynes is described.
- Altnau, G.,Roesch, L.,Bohlmann, F.,Lonitz, M.
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p. 4069 - 4072
(2007/10/02)
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