Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content.
1.1.6 SOMO and Radical Chemistry in Organocatalysis

DOI: 10.1055/sos-SD-204-00115

MacMillan, D. W. C.; Beeson, T. D.Science of Synthesis: Asymmetric Organocatalysis, (20121271.

General Introduction

One of the great advances that organocatalysis has brought to the field of synthetic chemistry is the introduction of several new modes of chemical activation through which hundreds of new asymmetric reactions have been discovered. For example, two of the earliest described organocatalytic activation modes, enamine catalysis[‌1‌,‌2‌] and iminium catalysis,[‌3‌‌5‌] both activate carbonyl compounds by reversible condensation with an amine catalyst. The former induces a HOMO-raising effect on the α-carbon to the carbonyl and generates a nucleophilic enamine species capable of α-functionalization by a variety of electrophiles. In contrast, iminium catalysis involves LUMO-lowering at the β-carbon of an α,β-unsaturated carbonyl creating an electrophilic iminium species capable of β-functionalization with a spectrum of nucleophiles (Scheme 1). Both of these concepts, while inducing reactivity analogous to that of Lewis acid catalysis,[‌6‌,‌7‌] have enabled many new and even historically unattainable enantioselective catalytic reactions (e.g., the aldehyde cross aldol via enamine catalysis[‌8‌]).

Meeeee 8 Meeee-Meeee Meeeeeeeee Meeee eee Meeeeeee Meeeeeeeeeeeeeeeee[‌8‌]

Meee eeeeeeee, e eeeee eeee ee eeeeeeee eeeeeeeeee eee eee α-eeeeeeeeeeeeeeeee ee eeeeeeee eeeeeeeee eeee eeeeeeee eeeeeee eeeeee ee eeeeeeeee eee eeee eeeeeeeee, eeeeee MMMM eeeeeeeee.[‌8‌,‌88‌] Meeeee eee eeeeeeeeeeee ee eee MMMM eee MMMM eeeeeeeee eeeeeeee eeeeeee ee eeeeeee eee eeeeeee eeeeeeeee, MMMM eeeeeeeee eeeeeeee ee eeeeeeeeeeeee eeeeee eeeeeeee eeeeeeeee eeeeeee ee eee eeeeeeee eeeeeeee, ee MMMM, ee eee eeee eeeeeee. MMMM eeeeeeeee eeeeee ee eee eeeeeeeee ee e eeeeeeee 8π-eeeeeeee eeeeeee eeeeee eeeeeee, eeeeeeee ee eeeeee-eeeeeeee eeeeeeeee ee e eeeeeeeeeeeee eeeeeeeee eeeeeee (Meeeee 8),[‌88‌,‌88‌] ee eee eeeeeeee ee e eeee eeeeee eeeeeeee ee eeeeeeee eeeeeeee eeeeeeee eee eeee eeeeeeee ee eeee eeeee eeeeeeee. Meeeeee, eee eeeeeeeeee eeeeeeeeee (MM) ee eee eeeeeeee eee eeeee eeeeeeee eeeeeeeeee (eeeee eeeeeee eee eeeeeeeeeee ee eeeeeeee)[‌88‌,‌88‌] eee eeeeeeeeeeee eeeeee eeee eeee ee eee eeeeeee eeeeee eeee eeee eeeeeeeee eeeeee ee eeeeeee eee eeeeeeeeeee eeeeeee eee eeeeeeeee eeeeeee eeeeeee (Meeeee 8). Me eeeeeeee ee eee eeeeee eeeeeee, eee 8π-eeeeeeee eeeeee ee eee MMMM eeeeeee eeeeee ee eeeeeeeeeeeee ee eeeeee eee eeeeeeeee eeeeee eeeeeee π-eeeeeee eee eeeeeeee eeee eeeeeeeeeeee eeeeeeeee (eeeeee MMMMeeeeee; Me), eeeeeee eeeeeeee ee eeeeeeee eee eeeee ee eeeeeeee α-eeeeeeeeeeeeeeeeee eeee eeeee eeeeeeeee eeeeeeee eee eee ee eeeeeee. Meee eee, eeeeee eeeeee eeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeee ee eeeeeeeee eeeee MMMM eeeeeeeee eeee eeee eeeeeeeeeeee, eeee ee eeeee eeee eeee eeeeeeee ee eee eeeeee α-eeeeeeeeeeeeeeeee ee eeeeeee.[‌8‌,‌88‌‌88‌]

Meeeee 8 Meeeeeeeeee Meeeeeeeee ee MMMM Meeeeeeee[‌8‌]

MMMM-eeeeeeeee eeeeeeeee eee eeeeeeeee eeeeeeeee ee eee-eeeeeee eeeeeeeeeeee eee eeeeeee ee ee eeeeeeeeeeeeeee eeeeeeee, e eeeeeeeeeeeeee eeeeeee, eeeee, eee e eeee eeeeeeee. Meeeee(MM), eeee(MMM), eee eeeeee(MM) eeeeeeee eeee eee eeee eeee eeeeeeeeeeee. Mee eeeeeeeee eee eeeeeeeeeeeee eee eeeeeee eeeeeeee eee eeeeeeeee eeeeeeee eee eeeee eeeeeeee. Mee eeeeeeee ee eeeee ee eee eeeeeeeee eee eeee eeeeeeeee ee eee eeee eeeeee eeeeeeee eeeeeeee, eee eeee eeeeeee ee eeeee eeeee eeeeeeee ee eee eeeeeee.[‌88‌] Meee eee eeeeeeeee ee eee eeeeeeee,[‌88‌,‌88‌] MMMM eeeeeeeee eeee ee eeeeeeeee eeeeeeeee ee eeeeeeeee eeeeee, e eeeee eeeeeee eeee.[‌88‌] Meee ee eeeeeeeee eeeeeeee ee eeeeeeeeee eee eeeeeeee eeeeee eee eeeeeeeeeee eeee eeeee eeeee eeeeeeee eeeeeeeeee, eeee eeeeeee ee eee eeeeeeee eeeeeee ee e eee eeeeee eeeeeeeeeee ee eeeeeee eeeeeeeeeee ee eee eeeeeee.

Meeeee eeeeeeeeeeeeeee eeeeeeeee eeee eeee eeeee eeeeeee ee eeee eeeeeee eee eeeeeee eeeeeeeee eee eeee-eee eee eeeeeeeee ee eeeeee eee MMMM-eeeeeeeee eeeeeeeee, eeee eee eeeeee-eeeeeeeeee eeeeeeeeeeeeeee eeeeeeee 8[‌88‌] eeeeee eeee eeee eeeeeeeeeeeee. Me eeeee ee Meeeee 8, eeeeeeeeeeeee eeeeeeeeeeeeee ee eeeeeee eeeee ee eee 8π-eeeeeeee eeeeee ee eee eeeeeee eeeeee eeeee eeeeeeee eeee eeee eee eeeee eeee-eeeee eeeeeeeeeee, eee eeeeeeee ee eeeeee eeeeeeeee ee eee Me eeee ee eee π-eeeeee ee eee eeeeeeee eeeeeeeeeee, eeeeeee eee Me eeee eeeeeee ee eee eeeeeeee MMMMeeeee. Mee eeeeeeeeeeeeeee eeeeeeeee eeee eeee eeee eeeeeeeee eee MMMM eeeeeeeee ee eeeeeee eeee eeee eeeeeee eeeeeeeee eeeee eee eeeeeeeee eeeeeeee eeeeeeeeee.[‌88‌]

Meeeee 8 Meeeeeeeeeeee Meeeeeeeeeeeee ee eee 8-Meeeee-8-eeee-eeeee-8-eeeeeeeeeeeeeeeeee-8-eee Meeeeeee[‌8‌]

References