syn-Selective crotylation of aldehydes using bismuth-crotyl bromide-(1-butyl-3-methylimidazolium bromide) combination: some synthetic applications
作者:Dibakar Goswami、Mrunesh R. Koli、Sucheta Chatterjee、Subrata Chattopadhyay、Anubha Sharma
DOI:10.1039/c7ob00626h
日期:——
The Bi-[bmim][Br] combination has been found to offer high syn-selectivity in the crotylation of aldehydes with crotylbromide using practically stoichiometric amounts of the reagents. The room temperature ionic liquid (RTIL), [bmim][Br], activated Bi metal in the presence of oxygen to produce crotylbismuthdibromide, which reacted with the aldehydes at room temperature. The major anti–syn diastereomeric
A facile general route to enantiomerically pure 3,4-cis-dialkyl-substituted gamma -lactones and 4,5-cis-dialkyl-substituted delta -lactones by TiCl4-mediated Evans asymmetric aldolization as the key step is exemplified by synthesis of cis-(3R,4R)-3-methyldecan-4-olide and (4R,5R)-aerangis lactone.
Synthesis of Natural Fragrant Molecules <i>cis</i>-3-Methyl-4-decanolide and Aerangis Lactone. General Enantioselective Routes to β,γ-<i>cis</i>-Disubstituted γ-Lactones and γ,δ-<i>cis</i>-Disubstituted δ-Lactones
作者:Yikang Wu、Xin Shen、Chao-Jun Tang、Zhi-Long Chen、Qi Hu、Wei Shi
DOI:10.1021/jo025540o
日期:2002.5.1
(S)-phenylalanine-derived 2-oxazolidinone or thiazolidinethione as chiralauxiliary, whereas the (S,S) ones were constructed with auxiliary prepared from (R)-phenylglycine. NaBH(4)/CaCl(2)/THF in the presence of a small amount of EtOH was introduced as a new effective method for reductive cleavage of chiral oxazolidinone auxiliaries. Previously unknown, tricky concentration effects were observed during the monotosylation