Stereo and electronic effects in the rhodium(II)-mediated synthesis of polycyclic lactones and lactams from .alpha.-diazo ester and amide precursors
摘要:
The rhodium(II) carboxylate catalyzed decomposition of several alpha-diazo esters and amides has been studied. A series of 5-keto-1-diazo acetates were prepared by acylation of alpha-hydroxy ketones using the (p-toluenesulfonyl)hydrazone of glyoxylic acid chloride. Treatment of these compounds with Rh(II) acetate afforded products derived from carbenoid insertion into solvent. When the hydrogen atom of the diazo carbon was replaced with an electron-withdrawing substituent, smooth cyclization occurred to produce a carbonyl ylide dipole which was subsequently trapped with different dipolarophiles. A series of N-alkyl-2-diazo-3-oxobutylamides, when treated with a catalytic quantity of rhodium(II) acetate, gave furo[3,4-c]furans in good yield. The reaction proceeds via addition of a rhodium-stabilized carbenoid onto the acetylenic pi-bond to give a vinyl carbenoid which subsequently cyclizes onto the neighboring carbonyl group to produce the furan ring. N-Alkynyl-substituted 2-diazoacetamides were also found to cyclize onto the tethered alkyne unit. The resulting rhodium carbenoid can undergo intramolecular and bimolecular cyclopropanation depending on both electronic and conformational factors. Rotamer population of the starting diazoamide was also found to influence product distribution.
DEAN, DENNIS C.;KRUMPA, KEITH E.;PADWA, ALBERT, J. CHEM. SOC. CHEM. COMMUN.,(1989) N4, C. 921-922
作者:DEAN, DENNIS C.、KRUMPA, KEITH E.、PADWA, ALBERT
DOI:——
日期:——
Stereo and electronic effects in the rhodium(II)-mediated synthesis of polycyclic lactones and lactams from .alpha.-diazo ester and amide precursors
作者:Albert Padwa、Dennis C. Dean、David J. Fairfax、Simon L. Xu
DOI:10.1021/jo00069a030
日期:1993.8
The rhodium(II) carboxylate catalyzed decomposition of several alpha-diazo esters and amides has been studied. A series of 5-keto-1-diazo acetates were prepared by acylation of alpha-hydroxy ketones using the (p-toluenesulfonyl)hydrazone of glyoxylic acid chloride. Treatment of these compounds with Rh(II) acetate afforded products derived from carbenoid insertion into solvent. When the hydrogen atom of the diazo carbon was replaced with an electron-withdrawing substituent, smooth cyclization occurred to produce a carbonyl ylide dipole which was subsequently trapped with different dipolarophiles. A series of N-alkyl-2-diazo-3-oxobutylamides, when treated with a catalytic quantity of rhodium(II) acetate, gave furo[3,4-c]furans in good yield. The reaction proceeds via addition of a rhodium-stabilized carbenoid onto the acetylenic pi-bond to give a vinyl carbenoid which subsequently cyclizes onto the neighboring carbonyl group to produce the furan ring. N-Alkynyl-substituted 2-diazoacetamides were also found to cyclize onto the tethered alkyne unit. The resulting rhodium carbenoid can undergo intramolecular and bimolecular cyclopropanation depending on both electronic and conformational factors. Rotamer population of the starting diazoamide was also found to influence product distribution.
Carbonyl ylide formation from the rhodium (<scp>II</scp>) acetate catalysed reaction of keto α-diazoacetate derivatives
作者:Dennis C. Dean、Keith E. Krumpe、Albert Padwa
DOI:10.1039/c39890000921
日期:——
Formation of carbonylylidesfrom the reaction of keto α-diazoacetates with rhodium (II) acetate has been found to be dependent on the electrophilicity of the intermediate rhodium carbenoid.