Trichloroacetylation of some cyclic enamines.
(1/19)
The pyrrolidine and morpholine enamines of cyclic ketones such as cyclohexanone and cyclopentanone were successfully diacetylated at alpha- and alpha'-positions with trichloroacetyl chloride using zinc catalyst. Morpholine enamines of the cyclic ketones gave acetylated morpholine in good yields besides the corresponding diacetylated cyclic enamines. When the same reactions were performed by using triethylamine without using zinc, monoacetylation products of the same enamines were synthesized. (+info)
Synthesis and hemolytic activity of some hederagenin diglycosides.
(2/19)
Glycosylation of hederagenin with the trichloroacetimidate derivatives of six commercial disaccharides (D-cellobiose, D-lactose, D-maltose, D-melibiose, D-gentiobiose, D-isomaltose) was performed giving the protected saponins in high yields. Deprotection then gave the saponins which were transformed into the corresponding methyl esters. The hemolytic activity of these synthetic hederagenin diglycosides was measured in order to establish structure-activity relationships based on the type and sequence of the attached sugar for the free carboxylic acid and methyl ester saponins. (+info)
Catalytic asymmetric synthesis of chiral allylic esters.
(3/19)
Trichloroacetimidate derivatives of prochiral (Z)-2-alken-1-ols react at room temperature with carboxylic acids to give chiral 3-acyloxy-1-alkenes in high enantiopurity in the presence of di-mu-acetatobis[(eta5-(S)-(pR)-2-(2'-(4'-methylethyl)oxazolinyl)cyclopentadienyl ,1-C,3'-N)(eta4-tetraphenylcyclobutadiene)cobalt]dipalladium (COP-OAc) or its enantiomer. This reaction has broad scope, proceeds with predictable high stereoinduction, is accomplished at room temperature using high substrate concentrations and low catalyst loadings, and likely proceeds by a novel mechanism. (+info)
Mechanism and selectivity of cinchona alkaloid catalyzed [1,3]-shifts of allylic trichloroacetimidates.
(4/19)
Synthesis of immunostimulatory alpha-C-galactosylceramide glycolipids via Sonogashira coupling, asymmetric epoxidation, and trichloroacetimidate-mediated epoxide opening.
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