Premium
Chelated Diborenes and Their Inverse‐Electron‐Demand Diels–Alder Reactions with Dienes
Author(s) -
Stennett Tom E.,
Mattock James D.,
Pentecost Leanne,
Vargas Alfredo,
Braunschweig Holger
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201809217
Subject(s) - alder , inverse , diels–alder reaction , chelation , electron , chemistry , organic chemistry , physics , catalysis , nuclear physics , mathematics , biology , botany , geometry
A doubly base‐stabilised diborane based on a benzylphosphine linker was prepared by a salt elimination reaction between 2‐LiC 6 H 4 CH 2 PCy 2 ⋅Et 2 O and B 2 Br 4 . This compound was reduced with KC 8 to its corresponding diborene, with the benzylphosphine forming a five‐membered chelate. The diborene reacts with butadiene, 2‐trimethylsiloxy‐1,3‐butadiene, and isoprene to form 4,5‐diboracyclohexenes, which interconvert between their 1,1‐ (geminal) and 1,2‐ (vicinal) chelated isomers. The 1,1‐chelated diborene undergoes a halide‐catalysed isomerisation into its thermodynamically favoured 1,2‐isomer, which undergoes Diels–Alder reactions more slowly than the kinetic product.