Ni-Catalyzed Si−B Addition to 1,3-Dienes:  Disproportionation in Lieu of Silaboration

Abstract

[reaction: see text] Upon attempted silaboration of acyclic 1- and 1,4-substituted 1,3-dienes, a new disproportionation reaction was discovered, yielding 1:1 mixtures of allylsilanes and dienylboranes. It was demonstrated that, as a key step in this new catalytic process, hydrogen is being transferred from one diene moiety to another.

Recent Advances in Boron‐Substituted 1,3‐Dienes Chemistry: Synthesis and Application

“…In 2006, Moberg et al . used nickel complexes (such as Ni(cod) 2 , or a complex prepared in situ from Ni(acac) 2 in the presence of DIBAL‐H and triethylphosphine) in the addition reaction of B–E to a linear 1,4‐substituted diene (Scheme ; Path I–III), and obtained a mixture of borylsilyllation products—borylsubstituted butadiene 126 , 129 , 132 and silyl‐substituted diene 125 , 128 , 131 .…”

“…In 2006, Moberg et al [104] used nickel complexes( such as Ni The same group proposedt he mechanism of Ni-catalyzed disproportionation of (E,E)-5,7-dodecadiene with as ilylborane process (Scheme 39). [104] The studies revealed that the key step in this new catalytic process was ah ydrogen transfer from one diene moietyt oa nother,ass hown in the Schemeb elow.…”

Enantioselective silicon–boron additions to cyclic 1,3-dienes catalyzed by the platinum group metal complexes

“…In contrast to the situation with linear 1,4-disubstituted 1,3-dienes, which provide 1:1 mixtures of dienylboranes and hydrosilylated products [20], only 1,4-silaborated adducts were obtained from the cyclic substrates. The product from addition of 2-(dimethylphenylsilyl)-4,4,5,5-tetrametyl-1,3,2-dioxaborolane to 1,3-cyclohexadiene was formed with 82% ee using a catalyst obtained by reduction of Pt(acac) 2 in the presence of a phosphoramidite with (R)-binaphthyl and dibenzylamino groups.…”

Silylboranes as New Tools in Organic Synthesis

“…40 They also reported that related nickel-catalyzed reaction of (dimethylphenylsilyl)pinacolborane (1c) with acyclic 1,4-disubstituted butadiene resulted in the formation of dienylboranes and allylic silanes as major products. 41 Platinum-catalyzed 1,4-silaboration of conjugated enynes having bulky substituents at the alkynyl carbons was also reported by Moberg's group. 42 5.3 Three-Compornent Coupling of Silylborane, 1,3-Diene, and Aldehyde.…”