Catalytic protodeboronation of pinacol boronic esters: formal anti-Markovnikov hydromethylation of alkenes

Abstract

Methane is formally added to alkenes via sequential hydroboration, Matteson-CH2-homologation and radical protodeboronation.

Radical‐Induced 1,2‐Migrations of Boron Ate Complexes

“…If α‐perfluoroalkylated ketones are formed as initial products after C−B to C=O functional group transformation, HF elimination was observed during purification leading to α,β‐unsaturated ketones. The high synthetic potential of the stereospecific radical‐induced 1,2‐boron ate rearrangement was further demonstrated by its application to novel formal total syntheses of δ‐( R )‐coniceine and indolizidine 209B, starting with the enantiopure Boc‐protected pyrrolidine boronic ester (Scheme b) . Via a radical polar crossover reaction using α‐iodoacetates as C‐radical precursors, two C−C‐bonds are formed in the key reaction.…”

Photoinduced Transition-Metal-Free Alkynylation of Alkyl Pinacol Boronates

“…Our group has been focusing on the development of new methods for the synthesis and application of alkyl-Bpin. [45][46][47][48][49][50][51][52] Considering the challenge of the less reactive Aggarwal group 41,42 Ley and co-workers [38][39][40] Studer group 43 Scheme 1 | (a and b) Photoinduced generation of alkyl radicals from alkyl-Bpin and its application in a transitionmetal-free alkynylation. LG = -SO 2 Ph.…”

“…The generated alkyl radicals reacted with olefins to form Csp 3 -Csp 3 bonds. The Studer group 43 also used this activation strategy to achieve protodeboronation of alkyl-Bpin. However, the preformation of ate complex using PhLi at low-temperature and solvent-switch operation make this strategy less practical.…”

An Efficient Deprotection of 2,6-Bis(trifluoromethyl)phenylboronic Esters via Catalytic Protodeboronation Using Tetrabutyl­ammonium Fluoride

“…Although the base-promoted protodeboronation 9 has been known as a side reaction in Suzuki-Miyaura coupling reactions, a few recent reports have revealed that the protodeboronation of organoboron compounds promoted by acid 10 or complexes containing metals, such as gold, 11 silver, 12 copper, 13 and bismuth, 14 can be applied in synthetic organic transformations. 15 Aggarwal 16,17 reported the protodeboronation of tertiary boronic esters with essentially complete retention of configuration, promoted by a stoichiometric amount of CsF,H 2 O-or TBAF•3H 2 O (Scheme 2). They suggest that the protodeboronation of boronic esters proceeds via protonation of a tetracoordinated borate intermediate generated by coordination of a fluoride anion to the boron atom of the boronic esters.…”