Z-Selective Horner−Wadsworth−Emmons Reaction of α-Substituted Ethyl (Diarylphosphono)acetates with Aldehydes1
摘要:
New Horner-Wadsworth-Emmons reagents, ethyl 2-(diarylphosphono)propionates (2), ethyl 2-(diarylphosphono)hexanoates (3), and ethyl 2-(diarylphosphono)-3-methylbutanoates (4) were prepared by alkylation of ethyl (diarylphosphono)acetates. The reaction of 2-4 with various types of aldehydes gave Z-alpha,beta-dialkyl-alpha,beta-unsaturated esters highly selectively. Remarkable temperature-dependent selectivity was observed in the reaction of (PhO)(2)P(O)CHBuCO2Et with octyl aldehyde.
Z-Selective Horner−Wadsworth−Emmons Reaction of α-Substituted Ethyl (Diarylphosphono)acetates with Aldehydes1
摘要:
New Horner-Wadsworth-Emmons reagents, ethyl 2-(diarylphosphono)propionates (2), ethyl 2-(diarylphosphono)hexanoates (3), and ethyl 2-(diarylphosphono)-3-methylbutanoates (4) were prepared by alkylation of ethyl (diarylphosphono)acetates. The reaction of 2-4 with various types of aldehydes gave Z-alpha,beta-dialkyl-alpha,beta-unsaturated esters highly selectively. Remarkable temperature-dependent selectivity was observed in the reaction of (PhO)(2)P(O)CHBuCO2Et with octyl aldehyde.
[structure: see text]. An enantiocontrolled totalsynthesis of (+)-lasonolide A has been accomplished by using the sequential cross metathesis and macrolactonization for the key assembly of the 20-membered polyene macrolide core of the natural product.
An efficient and enantiocontrolled synthesis of the C1-C16 segment of lasonolide A has been accomplished starting from a readily available optically pure aldehyde.
The first enantioselective total synthesis of penostatin E has been accomplished. Two highly efficient and diastereoselective reactions, a Hosomi–Sakurai allylation and an intramolecular Pauson–Khand reaction, were utilized for the construction of the basic carbon framework of the target molecule as the key steps. A late-stage introduction of the side chain and a successful base-promoted elimination
Enantioselective Total Synthesis of Macrolide Antitumor Agent (−)-Lasonolide A
作者:Arun K. Ghosh、Gangli Gong
DOI:10.1021/ol0701013
日期:2007.4.1
[structure: see text] An enantioselective totalsynthesis of (-)-lasonolide A is described. The upper tetrahydropyran ring was constructed stereoselectively by an intramolecular 1,3-dipolar cycloaddition reaction. The bicyclic isooxazoline led to the tetrahydropyran ring as well as the quaternary stereocenter present in the molecule. The lower tetrahydropyran ring was assembled by a catalytic asymmetric