Synthesis of azaspiro[4.5]decane systems by oxidative cyclization of olefinic precursors
作者:María J. Martín-López、Francisco Bermejo
DOI:10.1016/s0040-4020(98)00746-7
日期:1998.10
The synthesis of 6-benzyloxycarbonyl-1-oxa-6-azaspiro[4.5]decan-2-one (17) and 6-benzyloxycarbonyl-1,6-diazaspiro[4.5]decan-2-one (18) from the D,L-pipecolic acid derivative 10, is described. The synthesis of (±)-6-benzyl-3-methyl-1,6-diazaspiro[4.5]dec-3-ene-2,7-dione (29), the spiro structural unit of (±)-pandamarine (8) has been achieved by oxidative cylization of the (Z) and (E) isomers of 5-(N-
Amino acids as precursors to indolizidine alkaloids. DPPA-promoted decarbonylation of a bicyclic amino acid: An easy entry to hydroxylated indolizidines
作者:María J. Martín-López、Francisco Bermejo-González
DOI:10.1016/s0040-4039(00)78513-3
日期:1994.11
The synthesis of 8,8a-trans-8-hydroxy-indolizidine 12 from (D,L)-pipecolinic acid by two alternative routes is described. The stereospecific decarbonylation of the bicyclic carboxyamide 9 promoted by diphenylphosphorazidate (DPPA) is the key step of our strategy. The bicyclic enamide 10 is described as a valuable intermediate in the synthesis of hydroxylated indolizidines.
DPPA-Promoted decarbonylation of a N-Cbz-(D,L)-Pipecolinic acid derivative: An easy entry to [4.5]spirolactams and [4.5]spirolactones. Total synthesis of (±)-δ-coniceine
作者:M.J. Martín-López、F. Bermejo-González
DOI:10.1016/s0040-4039(00)73161-3
日期:1994.6
The synthesis of 6-benzyloxycarbonyl-1-oxa-6-azaspiro[4.5]decane-2-one 7a and 6-benzyloxycarbonyl-1,6-diazaspiro[4.5]decane-2-one 7b from (D,L)-pipecolinic acid is described. The extremely clean decarbonylation of the alpha-substituted amino acid 9d promoted by diphenylphosphorazidate (DPPA) is the key step of our strategy. The total synthesis of (+/-)-delta-coniceine (16) from the enamine ester 10a has been successfully achieved.