Ester enolate Claisen rearrangements of allyl .alpha.-fluoroacetates and .alpha.-fluoropropanoates
摘要:
The ester enolate Claisen rearrangement of allyl alpha-fluoroacetates 1 forms 2-fluoroalkenoic acids 2 in good to excellent yield with good internal asymmetric induction. This selectivity was unexpected as stereoselective deprotonation of fluoroacetates is not normally possible. The selective formation of the required alpha-fluoro silyl ketene acetal 3 was found to result from the stereoselective rearrangement of the allyl alpha-fluoro-alpha-silylacetate isomer. Although silyl ketene acetals derived from alpha-fluoropropanoates 7 also rearranged, control of internal asymmetric induction was not possible.
Facile diastereoselective ester enolate Claisen rearrangements of allyl fluoroacetates
作者:John T. Welch、Janet S. Samartino
DOI:10.1021/jo00219a056
日期:1985.9
The synthesis of 2,3-dideoxy-2-fluoro-3-C-methylpentose-containing nucleosides via [3,3]-sigmatropic rearrangements
作者:Koichi Araki、Wei Oin Yun、John O'Toole、Paul J. Toscano、John T. Welch
DOI:10.1016/0008-6215(93)84067-g
日期:1993.10
[3,3]-Sigmatropic rearrangement of in situ-formed [0,0]-silyl ketene acetals of butenyl fluoroacetates was used as the key step in the synthesis of racemic 2,3-dideoxy-2-fluoro-3-C-methylpentofuranoses. The product pentofuranoses were transformed further into pyrimidine and purine nucleosides. The conformations of the synthetic carbohydrates were confirmed by single-crystal X-ray diffraction studies and indicated that previous structural assignments made by NMR were in error.
Peptide modification by incorporation of α-trifluoromethyl substituted α-amino acids
作者:Klaus Burger、Norbert Sewald、Christian Schierlinger、Kerstin Mütze、Liza C. Seymour
DOI:10.1016/s0022-1139(00)83708-2
日期:1991.9
WELCH, JOHN T.;PLUMMER, JANET S.;CHOU, TSO-SHENG, J. ORG. CHEM., 56,(1991) N, C. 353-359
作者:WELCH, JOHN T.、PLUMMER, JANET S.、CHOU, TSO-SHENG
DOI:——
日期:——
WELCH, J. T.;SAMARTINO, J. S., J. ORG. CHEM., 1985, 50, N 19, 3663-3665