Asymmetric Pericyclic Cascade Approach to Spirocyclic Oxindoles
摘要:
The reaction of chiral N-arylnitrones with carbocyclic alkylarylketenes generates spirocyclic oxindoles in good yields and with excellent levels of enantioselectivity (90-99% ee) via a pericyclic cascade process.
Pericyclic Cascade with Chirality Transfer: Reaction Pathway and Origin of Enantioselectivity of the Hetero-Claisen Approach to Oxindoles
作者:Nihan Çelebi-Ölçüm、Yu-hong Lam、Edward Richmond、Kenneth B. Ling、Andrew D. Smith、Kendall N. Houk
DOI:10.1002/anie.201105412
日期:2011.11.25
for the chiral auxiliary‐controlled synthesis of 3,3‐disubstituted oxindoles from nitrones and ketenes. The remarkable acyclic 1,6‐stereochemical induction, hitherto unexplained, is rationalized by a stereoselective 3+2 cycloaddition step, which installs the stereochemistry, and a chirality transfer step facilitated by a hetero‐[3,3]‐sigmatropic rearrangement (see picture; PG=protectinggroup).