- Formal Synthesis of (-)-Quinagolide: Diastereoselective Ring Expansion via a Bicyclic Aziridinium Ion Strategy to Access the Octahydrobenzo[ g]quinoline Architecture
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The diastereoselective formal synthesis of (-)-quinagolide, a D2 receptor agonist, has been achieved. The synthesis started from l-pyroglutamic acid and relied on utilization of (a) a stereospecific catalytic hydrogenation and diastereoselective Horner-Emmons-Michael cascade to obtain functionalized prolinate, (b) a Lewis acid mediated Pummerer cyclization to construct a tricyclic fused ring system, and (c) a diastereoselective ring expansion via a bicyclic aziridinium intermediate to access the required 3-substituted piperidine scaffold.
- Chavan, Subhash P.,Gonnade, Rajesh G.,Kadam, Appasaheb L.,Kawale, Sanket A.,Pisal, Mahesh M.
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- ISOTHIOCYANATE COMPOUND AND APPLICATION THEREOF
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The present invention provides an isothiocyanate compound and its application. The compound is an aryl-substituted isothiocyanate compound that has a structure of the general formula I. The isothiocyanate compound of the present invention has very good solubility in water, far better inhibitory activity for XPO1 protein than other non-aryl substituted congeneric compounds, little side effects, and good biological safety and bioavailability, and is quite suitable for clinical application. Therefore, the isothiocyanate compound would have tremendous potential market space and economic benefits.
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- Dipolar vinyl sulfur fluorescent dyes. Synthesis and photophysics of sulfide, sulfoxide and sulfone based D-π-A compounds
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New vinyl sulfides and sulfoxides were obtained in good yields using the Horner-Wadsworth-Emmons (HWE) reaction. The vinyl sulfides and sulfoxides presented preferentially the E-stereochemistry. The respective vinyl sulfones were obtained in good yields from the vinyl sulfides by a simple oxidation step using mCPBA, solely as the E isomers. These derivatives presented absorption maxima in the UV-A region with molar absorptivity coefficients and radiative rate constant values ascribed to spin and symmetry-allowed 1π-π* electronic transitions. Experimentally, a small solvatochromic effect indicated an almost absent charge transfer character in the ground-state. A fluorescence emission in the violet-green region with a significative redshift on the maxima with increasing solvent polarity was observed, which could be related to a better electron delocalization in the excited state, as a result of an intramolecular charge transfer state. DFT and TD-DFT calculations were performed at the PBE1PBE and CAM-B3LYP levels of theory. No solvatochromic effect was observed in the ground state, but a bathochromic effect was detected in the emission maxima. Starting from sulfides to sulfones, the addition of oxygen atoms improved the charge separation, enabling an ICT state, mainly in P3 and P5. This charge separation was more efficient in the triphenylamino derivatives than among the pyrene derivatives since the first one has a better electron-donating character.
- Mon?alves, Matias,Zanotto, Gabriel M.,Toldo, Josene M.,Rampon, Daniel S.,Schneider, Paulo H.,Gon?alves, Paulo F. B.,Rodembusch, Fabiano S.,Silveira, Claudio C.
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p. 8832 - 8842
(2017/02/10)
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- An Efficient Protecting-Group-Free Synthesis of Vinylic Sulfoximines via Horner-Wadsworth-Emmons Reaction
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Herein, we report a convenient synthesis of aryl-substituted (E)-vinylic NH-sulfoximines via the Horner-Wadsworth-Emmons reaction without the use of protection-deprotection group strategies.
- Chinthakindi, Praveen K.,Nandi, Ganesh Chandra,Govender, Thavendran,Kruger, Hendrik G.,Naicker, Tricia,Arvidsson, Per I.
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p. 1423 - 1427
(2016/05/24)
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- A Diels-Alder approach to biaryls (DAB): synthesis of the western portion of TMC-95
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The rapid synthesis of the western biaryl portion of TMC-95 is disclosed via the use of a Diels-Alder reaction with o-nitrostyrene derivative and 1-silyloxy diene with excellent regiochemical control. Subsequent sequential substitutions of a p-iodo-phenol
- Ashburn, Bradley O.,Rathbone, Lauren K.,Camp, Elizabeth H.,Carter, Rich G.
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p. 856 - 865
(2008/09/16)
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- A conjugate addition/sulfoxide elimination route to allylic difluorophosphonates
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Cerium-mediated conjugate additions of (diethoxyphosphinoyl) difluoromethyllithium to cyclic vinyl sulfoxides proceeded smoothly; thermal sulfoxide elimination afforded the products of formal vinylation, attaching the difluoromethylenephosphonato group to an alkenyl carbon atom. With acyclic vinyl sulfoxides, the addition occurred in moderate to poor yield. Addition failed completely in the absence of cerium(III) chloride, and was facilitated by an excess of the reagent.
- Blades, Kevin,Percy, Jonathan M.
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p. 9085 - 9088
(2007/10/03)
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- Oxidation of Sulfides to Sulfoxides with Hypervalent (tert-Butylperoxy)iodanes
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Oxidation of sulfides with the crystalline (alkylperoxy)iodanes, 1-(tert-butylperoxy)-1,2-benziodoxol-3(1H)-ones 2a and 2b, in acetonitrile-water or in dichloromethane, affords sulfoxides in high yields. Measurement of the relative rates of oxidation for a series of ring-substituted thioanisoles 3b (p-MeO), 3c (p-Me), and 3d (p-Cl) in acetonitrile-water indicates that electron-releasing groups such as p-MeO and p-Me groups increase the rate of oxidation, and Hammett correlation of the relative rate factors with the substituent constants affords the reaction constants ρ+ = -2.23 (σ+, r = 0.98) for BF3-catalyzed oxidation and ρ = -3.32 (σ, r = 0.98) for uncatalyzed oxidation. The effects of a free-radical scavenger, galvinoxyl, were examined. A mechanism involving the intermediary formation of the sulfonium species 11 by nucleophilic attack of sulfide toward the iodine(III) atom of 2 is proposed for the oxidation in acetonitrile-water in the presence and the absence of BF3· Et2O. On the other hand, the oxidation of sulfoxides in dichloromethane probably proceeds by a radical process, which involves the decomposition at room temperature of 2 via homolytic bond cleavage of the weak iodine(III)-peroxy bond, generating tert-butylperoxy radical and the [9-1-2] iodanyl radical 12.
- Ochiai, Masahito,Nakanishi, Akinobu,Ito, Takao
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p. 4253 - 4259
(2007/10/03)
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- α-HALOGENO SULPHOXIDES AS AMBIDENT ELECTROPHILES TOWARDS DIALKYL PHOSPHITE ANIONS
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α-Halogenomethyl alkyl(aryl) sulphoxides have been found to undergo nucleophilic attack by dialkyl phosphite anions at the α-carbon atom and/or at halogen.
- Mikolajczyk, Marian,Zatorski, Andrzej
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p. 323 - 324
(2007/10/02)
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- Free radical desulfenylation and deselenylation of α-sulfur and α-seleno substituted phosphonates with the n-Bu3SnH/AIBN reagents system.
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Selestive desulfenylation and deselenylation of α-sulfur- and α-seleno-substituted phosphonates under free radical condition are described.Chemoselectivity and scope of title reaction were studied using phosphonates additionaly functionalized in the α-position alkyl, phenyl,ethoxy,chloro,carbonyl and sulfenyl groups.It was found the reduction of a halogen tolerates the presence of the sulfenyl group and the latter could be reduced in the presence of the sulfinyl and sulfonyl moieties.Moreover,one sulfenyl group was selectively removed from α-phosphoryl dithioacetals and the phenylsulphenyl group was reduced preferentially in the presence of the methylsulfenyl one. Key words:Desulfenylation,deselenylation,α-phosphoryl sulfides,α-phosphoryl selenides, tri-n-butyltinhydride,α,α-azaisobutyronitrile.
- Balczewski,Piotr
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p. 113 - 122
(2007/10/03)
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- Approaches to the Synthesis of Retronecine from Some Pyrrolidine Precursors
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Procedures are described for the attempted conversion of the pyrrolidine (2) into a bicyclic system that would ultimately lead to retronecine (3). The only molecule to be isolated from these attempts was the epimeric ketone (6), and AM1 and MM2 calculations were used to probe this apparently favoured isomerization. Alternative procedures were then investigated that sought to convert the pyrrolidine (1) into precursors to retronecine, and notable successes were obtained with the addition of the amine (21) to both nitroethene and ethyl 2-diethylphosphonoacrylate. However, not only were these precursors resistant to further transformations into retronecine, but also the problem of epimerization again arose. Consequently, AM1 calculations were again employed, and an X-ray structure determination of ethyl (7R,8R)-7-benzyloxy-1-benzyloxymethyl-5,6,7,8-tetrahydro-3H-pyrrolizine-2-carboxylate (39) is reported. Attempts to convert (39) into a diastereoisomer of retronecine were unsuccessful.
- Clare, Brian W.,Ferro, Vito,Skelton, Brian W.,Stick, Robert V.,White, Allan H.
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p. 805 - 824
(2007/10/02)
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- A Convenient Procedure for the Oxidation of Sterically Hindered Sulfides to Sulfoxides
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A selective and efficient method for the oxidation of sterically hindered sulfides to sulfoxides is described, which involves the use of hydrogen peroxide in methanol in the presence of catalytic amounts of a mixture of sulfuric acid and isoamyl, isopropy
- Drabowicz, Jozef,Lyzwa, Piotr,Popielarczyk, Miroslaw,Mikolajczyk, Marian
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p. 937 - 938
(2007/10/02)
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- Synthesis of α,β-γ,δ-unsaturated sulfones and sulfoxides via the Horner-Emmons reaction
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α,β-γ,δ-Unsaturated sulfones and sulfoxides have been prepared via the Horner-Emmons reaction of α,β-unsaturated carbonyl compounds with α-phosphoryl sulfones and sulfoxides.
- Jong, B. E. de,Koning, H. de,Huisman, H. O.
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p. 410 - 414
(2007/10/02)
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