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Efficient methods for the stereoselective synthesis of polyfunctional (E)- and (2)-alkenes and conjugated (EE)- and (E,2)-dienones are presented. They rely upon one-pot, four-component processes that condense 1-oxy-1,3-dienes, silyl enol ethers, SO2, and c ...
The importance of catalysis in chemistry has not to be proved anymore. Be it homogeneous or heterogeneous catalysis, the constant progresses observed in that field proves its obvious interest. The asymmetric homogeneous catalysis is a method of choice to s ...
N-Benzyloxycarbonyl-2,5-dideoxy-2,5-imino-3,4-O-isopropylidene-L-ribose 12a has been converted into (1R,2S,6R, 7S,7aS)-5 and (1R, 2S, 6S, 7R, 7aR)-1,2,6,7-tetrahydroxypyrrolidin-5-ones 6 and (1R,2S,6S,7S,7aS)-7 and (1R,2S,6R,7R,7aS)-1,2,6,7-tetrahydroxypyr ...
The reaction of aldehydes and ketones, including aliph. and arom. ones, with amides of alpha -isocyano-beta -phenylpropionic acid in toluene in the presence of lithium bromide gives 2,4,5-trisubstituted oxazoles in good to excellent yield. Protected chiral ...
A new sulfur dioxide-based organic chemistry has been developed as a novel approach for the stereoselective synthesis of polyene fragments based on our one-pot, four-component synthesis of polyfunctional alpha-alkanesulfonyl-gamma,delta-unsaturated ketones ...
The first aza-C-disaccharide (D-azaMan-beta-CHz-(1 -> 6)-D-Man-alpha-OMe) that mimicks alpha-D-Manp-(1 -> 6)-alpha-D-ManOMe was made in 1994 by Johnson and coworkers. Several synthetic approaches to these disaccharide mimetics have been proposed. These are ...
New conditions have been found for the desulfitative Mizoroki-Heck arylation and trifluoromethylation of mono- and disubustituted olefins with arenesulfonyl and trifluoromethanesulfonyl chlorides. Thus (E)1,2-disubstituted alkenes with high stereoselectivi ...
Quick access to polyfunctional spiroketal (3R)-4-[(2S,6R,8R, 10S)-4,4-bis(ethylthio)-10-hydroxy-8-(2-hydroxyethyl)- 1,7-dioxaspiro[5.5]undec-2-yl]butane- 1,3-diol [(+)-19] is now available through the stereoselective functionalization of enantiomerically p ...
Synthesis of orthogonally protected (2S,4R)- and (2S,4S)-4-hydroxyornithines I is reported featuring an asym. alkylation of N-(diphenylmethylene)glycine tert-Bu ester with (5S)-N-benzyloxycarbonyl-5-iodomethyl oxazolidine. Double stereoselection was examd. ...
A new route for the preparation of four new indolizidines, (1R,2S,6S,7S,8aS)- and (1R,2S,6R,7R,8aS)-1,2,6,7-tetrahydroxyindolizidine (30 and 32) and (1S,2R,7S,8S,8a-R)- and (1S,2R,7R,8R,8a-R)1,2,7,8-tetrahydroxyindolizidine (44 and 46), is reported. The sy ...
