Enantioselective Organo-SOMO Catalysis:  The α-Vinylation of Aldehydes

Abstract

Supporting InformationGeneral Information. Commercial reagents were purified prior to use following the guidelines of Perrin and Armarego. 1 All solvents were purified according to the method of Grubbs. 2 Organic solutions were concentrated under reduced pressure on a Büchi rotary evaporator using an ice-water bath for volatile compounds. Potassium trifluoroborate salts were synthesized from commercially or readily available boronic acids or esters using a modified Molander procedure. 3 Chromatographic purification of products was accomplished using force-flow chromatography on Silicycle silica gel according to the method of Still 4 and where noted, Iatrobeads 6RS-8060 was used in place of silica gel. Thin-layer chromatography (TLC) was performed on Silicycle 250 µm silica gel plates. Visualization of the developed chromatogram was performed by fluorescence quenching and anisaldehyde stain. 1 H and 13 C NMR spectra were recorded on a Varian Inova 400 (400 MHz or 100 MHz) and are internally referenced to residual protio solvent signals (note: CDCl 3

Improved method for the conversion of pinacolboronic esters into trifluoroborate salts: facile synthesis of chiral secondary and tertiary trifluoroborates

“…3 Rhodium-catalyzed 1,2-and 1,4-additions of organotrifluoroborate salts to aldehydes and Michael acceptors are also well established reactions. 4 Recently, enantioselective organocatalytic Michael additions of vinyl-and heteroaryltrifluoroborates to prochiral enals 5 and a-vinylations of aldehydes with vinyltrifluoroborates 6 have been reported. Furthermore, Matteson has reported the first example of the preparation of chiral secondary trifluoroborates and their conversion into amines.…”

Anodic Oxidation and Organocatalysis: Direct Regio‐ and Stereoselective Access to meta‐Substituted Anilines by α‐Arylation of Aldehydes

“…Many catalytic asymmetric processes are based on metal complexes and rely on activation modes such as Lewis acid catalysis, atom-transfer catalysis, as well as s-and p-bond insertions. Recently, organocatalysis [1] has emerged as a powerful source of enantioselective transformations and has led to the development of a-,[2] b-, [3] g-, [4] and SOMOactivations, [5] as well as cascade, domino, and tandem reactions. [6] Aromatic compounds are ubiquitous as medicines and functionalized materials, and are often formed by electrophilic substitution reactions.…”

Enantioselective Organo-Singly Occupied Molecular Orbital Catalysis: The Carbo-oxidation of Styrenes

“…1 Recently, our laboratory introduced a new mode of organocatalytic activation, termed (singly occupied molecular orbital) SOMO catalysis,2 that is founded upon the transient production of a 3π-electron radical-cation3 species that can function as a generic platform of induction and reactivity. As part of these studies, we documented the first direct and enantioselective allylic alkylation,2 enolation,4 and vinylation5 of aldehydes, three protocols that were not previously known in a chiral or achiral format. Continuing this theme, we recently questioned whether feedstock olefins, such as styrenes, might be exploited in this SOMO pathway to allow the enantioselective α-homobenzylation of aldehydes, a new C–C bond-forming reaction between functional groups that are generally inert to chemical combination.…”