Regio- and diastereocontrolled C–H insertion of chiral γ- and δ-lactam diazoacetates. Application to the asymmetric synthesis of (8S,8aS)-8-hydroxyindolizidine
Regio- and diastereocontrolled C–H insertion of chiral γ- and δ-lactam diazoacetates. Application to the asymmetric synthesis of (8S,8aS)-8-hydroxyindolizidine
Nonracemic Bicyclic Lactam Lactones via Regio- and <i>cis</i>-Diastereocontrolled C−H Insertion. Asymmetric Synthesis of (8<i>S</i>,8a<i>S</i>)-Octahydroindolizidin-8-ol and (1<i>S</i>,8a<i>S</i>)-Octahydroindolizidin-1-ol
作者:Andrew G. H. Wee、Gao-Jun Fan、Hypolite M. Bayirinoba
DOI:10.1021/jo901790g
日期:2009.11.6
The Rh-2(MPPIM)(4)-catalyzed intraniolecular C-H insertion reaction of (S)- and (R)-1-benzyl-5-(alpha-diazoacetoxy)piperidin-2-one and (S)-1-benzyl-4-(alpha-diazoacetoxy)pyrrolidin-2-one proceeds with high regioselectivity and cis-diastereoselectivity to give good yields of chiral nonracemic bicyclic lactam lactones (BLLs). For (S)- and (R)-1-benzyl-5-(alpha-diazoacetoxy)piperidin-2-one, the regio selectivity of the C-H insertion is catalyst-dependent; for example, (S)-1-benzyl-5-(alpha-diazoacetoxy)piperidin-2-one undergoes C-H insertion at C-6 preferentially when Rh-2(5S-MPPIM)(4) is used, but with Rh-2(5R-MPPIM)(4), C-H insertion occurs preferentially at C-4. This effect is not observed in the reaction of (S)-1-benzyl-4-(alpha-diazoacetoxy)pyrrolidin-2-one. The utility of the BLLs as chiral building blocks in alkaloid synthesis is exemplified by the synthesis of (8S,8aS)-octahydroindolizidin-8-ol and (1S,8aS)-octahydroindolizidin-1-ol.
Regio- and diastereocontrolled C–H insertion of chiral γ- and δ-lactam diazoacetates. Application to the asymmetric synthesis of (8S,8aS)-8-hydroxyindolizidine
作者:Gao-jun Fan、Zhongyi Wang、Andrew G. H. Wee
DOI:10.1039/b606436a
日期:——
γ- and δ-Lactam diazoacetates undergo efficient intramolecular CâH insertion catalyzed by Rh2(MPPIM)4 with excellent regioselectivity and cis-diastereoselectivity to provide synthetically useful bicyclic lactam lactones.