A new alternative system for the chemoselective oxidation of secondary hydroxyl group to ketone with IBX/n-Bu4NBr in CH2Cl2–H2O has been developed. Under the reaction conditions, the secondary hydroxyl group was highly chemoselectively oxidized to the corresponding ketone, in moderate to good yields at rt, in the presence of primary hydroxyl group within the same molecule.
<i>N</i>-phenyl-substituted pyrrolidines, piperidines and azabicyclics by a tandem reduction-double reductive amination reaction
作者:Richard A. Bunce、Derrick M. Herron、Jason R. Lewis、Sharadsrikar V. Kotturi
DOI:10.1002/jhet.5570400115
日期:2003.1
formed in high yield and are easily purified. The method has also been extended to the synthesis of fused N-phenylazabicyclics from 2-(3-oxo-propyl)cycloalkanones. A high degree of diastereoselectivity for the trans-fused product is observed in substrates having an ester group α to the cycloalkanone carbonyl. Bicyclic precursors lacking this ester group give mixtures of cis and trans products. Finally
Asymmetric Sequential Allylic
Transfer Strategy for the Synthesis of (-)-Adaline
and (-)-Euphococcinine
作者:Chan-Mo Yu、Bobin Lee、Jisook Kwon
DOI:10.1055/s-0029-1217172
日期:——
Enantioselective synthesis of the piperidine alkaloids, (-)-adaline (1) and (-)-euphococcinine (2), were achieved from 7 in a six-step sequence through stepwise allylic transfer reactions. Dramatic additive effect of Bu3SnF for the conversion of 3 into 9 was observed to expedite the process to afford the cyclized products in good yields.
Convenient Formation of 4-Hydroxyalk-2-en-1-one Functionality via A Knoevenagel-type Carbon Chain Elongation Reaction of Aldehyde with 1-Arylsulfinylalkan-2-one
A highly functionalized four-carbon unit, 4-hydroxyalk-2-en-1-one functionality [(RCH)-C-2(OH)CH=CHCOR1], was conveniently prepared by a reaction of an aldehyde ((RCH2CHO)-C-2) with a 1-(arylsulfinyl)alkan-2-one [ArS(O)CH2COR1] in the presence of diethylamine (Knoevenagel condition). Other functional groups, such as carbonyl and hydroxy groups, in both of the alkyl chains (R-1, R-2) did not prevent this reaction. This reaction was used to conveniently prepare (+/-)-(11E)-13-hydroxy-10-oxooctadec-11-enoic acid (14), having cytotoxic activity, and its analogues from undec-10-enoic acid in good yield.