The macrocyclic antibiotic mangrolide A has been described to exhibit potent activity against a number of clinically important Gram‐negative pathogens. Reported is the first enantioselective totalsynthesis of mangrolide A and derivatives. Salient features of this synthesis include a highly convergent macrocycle preparation, stereoselective synthesis of the disaccharide moiety, and two β‐selective
Stereospecific synthesis of branched-chain sugars by a novel aldol-type cyclocondensation
作者:María-Jesús Pérez-Pérez、María-José Camarasa、Angel Díaz-Ortiz、Ana San Félix、Federico G. de las Heras
DOI:10.1016/0008-6215(92)84176-s
日期:1992.9
Abstract A procedure for the preparation of branched-chainsugars having highly functionalised C -branches is reported. Reaction of furanos-3-uloses, pyranos-3-uloses, or pyranos-2-uloses with sodium cyanide followed by mesylation of the corresponding cyanohydrin afforded α-mesyloxynitriles which, on treatment with base, underwent aldol-type cyclocondensation to yield furanose-3-spiro-, pyranose-3-spiro-
SnCl4 Promoted Efficient Cleavage of Acetal/Ketal Groups with the Assistance of Water in CH2Cl2
作者:Tao Luo、Tian-Tian Xu、Yang-Fan Guo、Hai Dong
DOI:10.3390/molecules27238258
日期:——
carbohydrates containing acetal/ketal groups with the assistance of water in CH2Cl2 led to deacetalization/deketalization products in almost quantitative yields. In addition, for substrates containing both acetal/ketal and p-methoxylbenzyl groups, we also found that the p-methoxylbenzyl group was selectively cleaved by the use of a catalytic amount of SnCl4, while the acetal/ketal groups remained. Furthermore
Selective Deprotection Method of <i>N</i>-Phenylcarbamoyl Group
作者:Shoji Akai、Rika Tanaka、Hidekazu Hoshi、Ken-ichi Sato
DOI:10.1021/jo4007128
日期:2013.9.6
We report an improved method for the selective deprotection of the N-phenylcarbamoyl group, which yields the corresponding alcohol without affecting other protecting groups. Deprotection was performed using di-tert-butyl dicarbonate and tetra-n-butylammonium nitrite (Boc(2)O and Bu4NNO2) in pyridine at room temperature. This method is also effective for deprotecting the fluorous N-phenylcarbamoyl group.
Out-of-ring Claisen rearrangements are highly stereoselective in pyranoses: routes to gem-dialkylated sugars