Affiliation:
1. Department of Chemistry School of Science Loughborough University Loughborough Leicestershire LE11 3TU UK
2. Department of Chemistry Perm State University Bukireva 15 Perm 614990 Russia
3. N. D. Zelinsky Institute of Organic Chemistry Russian Academy of Sciences Leninsky prospect 47 Moscow 119991 Russia
Abstract
AbstractMetal‐catalyzed asymmetric alkylation of indoles with α‐diazoesters is well‐known, however, the underlying mechanisms of this reaction, particularly the origin of stereoselectivity, remain uncertain. For the Pd catalysis, we address this cutting‐edge challenge from two complementary viewpoints – i) the molecular level regarding a single catalytically active Pd center; and ii) nano‐level Pd species investigating the factors favoring the appearance of the preferred catalytic centers. The formation of the active catalytic species was monitored by structural methods (NMR and ESI‐MS), and metal particles were characterized with electron microscopy (SEM, EDX). On the molecular level, chiral bipyridine‐N,N’‐dioxides proved to be competent chiral controllers. The kinetic and DFT computational data revealed a crucial role of water in the rate and selectivity determining steps and showed that the enantioselectivity of the process is controlled by the protodepalladation step. On the nano‐scale, the important effect of catalyst precursor on the overall reaction performance was shown.
Funder
Engineering and Physical Sciences Research Council
Russian Science Foundation