Au-Catalyzed Asymmetric Formal [3 + 2] Cycloaddition of Isocyanoacetates with Maleimides
摘要:
An efficient protocol for the Au-I-catalyzed asymmetric formal [3 + 2] cycloaddition of isocyanoacetates with phenylmaleimide has been developed. In the presence of cationic Au-I/DTBM-segphos complex, excellent diastereoselectivity and high levels of enantioselectivity (up to 97% cc) have been attained with a variety of alpha-substituted isocyanoacetates. The synthetic potential of the resulting enantioenriched 1-pyrrolines has been demonstrated by the preparation of highly substituted pyrrolidines bearing a quaternary stereocenter.
Silver acetate catalysed cycloadditions of isocyanoacetates
作者:Ronald Grigg、Mark I. Lansdell、Mark Thornton-Pett
DOI:10.1016/s0040-4020(98)01216-2
日期:1999.2
Silveracetate is an efficient catalyst for the cycloaddition of methyl isocyanoacetate with Michael-acceptors under mild conditions to give Δ1- or Δ2-pyrrolines in good yields. In the case of acrolein, novel chemoselectivity was observed. In the absence of a suitable olefin isocyanoacetates undergo silveracetate catalysed cyclodimerisation to give imidazoles in excellent yields. The mechanism of