Diastereoselective Synthesis of 2-Amino-4-phosphonobutanoic Acids by Conjugate Addition of Lithiated Schöllkopf's Bislactim Ethers to Vinylphosphonates
作者:María Ruiz、M. Carmen Fernández、Aniana Díaz、José M. Quintela、Vicente Ojea
DOI:10.1021/jo034707q
日期:2003.10.1
Conjugateadditions of lithiatedbislactimethers derived from cyclo-[Gly-Val] and cyclo-[Ala-Val] to alpha-, beta-, or alpha,beta-substituted vinylphosphonates allow direct and stereoselective access to a variety of 3- or 4-monosubstituted and 2,3-, 2,4-, or 3,4-disubstituted 2-amino-4-phosphonobutanoic acids (AP4 derivatives) in enantiomerically pure form. The relative stereochemistry was assigned
A Catalytic Michael/Horner-Wadsworth-Emmons Cascade Reaction for Enantioselective Synthesis of Thiochromenes
作者:Abhijnan Ray Choudhury、Santanu Mukherjee
DOI:10.1002/adsc.201300281
日期:2013.7.8
A catalyticenantioselective sulfa‐Michael/Horner–Wadsworth–Emmonsreactioncascade has been developed, taking advantage of phosphonate as an electrophilic activator and a traceless binding site. Using a chiral bifunctional urea derivative as the catalyst, a variety of aryl and heteroaryl substituted thiochromenes was obtained in excellent yield with a high level of enantioselectivity.
malononitrile to vinyl phosphonates was accomplished by hydrogen bond-enhanced bifunctional halogen bond (XB) catalysis. NMR titration experiments were used to demonstrate that halogen bonding, with the support of hydrogen-bonding, played a key role in the activation of the Michael acceptors through the phosphonate group. This is the first example of the use of XBs for the activation of organophosphorus
Treatment of aromatic α-phosphorylacrylate derivatives 1a-h with Mg turnings in the presence of trimethylsilyl chloride brought about facile and regioselective C-silylation to give the corresponding β-silylated phosphonates 2a-h in excellent yields. The reaction took place smoothly for activated olefins possessing appropriate reduction potentials and may be initiated by electron transfer from Mg to 1a-h.
New, Simple and Versatile Synthesis of Protected α-Alkylidene-β-amino Acids from Activated Vinylphosphonates
作者:Tomasz Janecki、Tomasz Wąsek、Jacek Olczak
DOI:10.1055/s-2006-944184
日期:2006.6
A two-step route to Boc-protected α-alkylidene-β-amino esters was developed by addition of sodium tert-butylcarbamate to ethyl 2-diethoxyphosphoryl-2-alkenoates followed by the Horner-Wadsworth-Emmons olefination of aldehydes using intermediate 2-diethoxyphosphoryl-3-tert-butoxycarbonylaminoalkanoates.