TY - JOUR
T1 - Synthesis and reactions of optically active phosphine‐boranes
AU - Imamoto, Tsuneo
AU - Oshiki, Toshiyuki
AU - Onozawa, Takashi
AU - Matsuo, Masatoshi
AU - Hikosaka, Takaaki
AU - Yanagawa, Masao
PY - 1992
Y1 - 1992
N2 - Synthesis and reactions of optically active phosphine‐boranes have been investigated. Optically active secondary phosphine‐boranes, (Sp)‐and (Rp)‐menthyloxyphenylphosphine‐boranes, and (S)‐methylphenylphosphine‐borane underwent palla‐dium(0)‐catalyzed electrophilic arylation with o‐, m‐, or p‐iodoanisole. The stereochemistry of this arylation was largely dependent on the solvent and the base used. The reaction in acetonitrile proceeded with almost complete retention of configuration at the chiral phosphorus, whereas inversion of configuration was observed in ethereal solvents or toluene. The phosphorus‐oxygen bond of (Rp)‐menthyloxy (methyl) phenylphosphine‐borane and (SP)‐menthy‐loxy(o‐methoxyphenyl)phenylphosphine‐boranewas reductively cleaved at −78°C by lithium naphtha‐lenide or Li/NH3 with virtually net retention of configuration at phosphorus, providing secondary or tertiary phosphine‐boranes in excellent yields. New synthetic routes to optically pure C2‐symmetric bisphosphine‐boranes possessing chirality at phosphorus have been developed on the basis of these stereochemical studies.
AB - Synthesis and reactions of optically active phosphine‐boranes have been investigated. Optically active secondary phosphine‐boranes, (Sp)‐and (Rp)‐menthyloxyphenylphosphine‐boranes, and (S)‐methylphenylphosphine‐borane underwent palla‐dium(0)‐catalyzed electrophilic arylation with o‐, m‐, or p‐iodoanisole. The stereochemistry of this arylation was largely dependent on the solvent and the base used. The reaction in acetonitrile proceeded with almost complete retention of configuration at the chiral phosphorus, whereas inversion of configuration was observed in ethereal solvents or toluene. The phosphorus‐oxygen bond of (Rp)‐menthyloxy (methyl) phenylphosphine‐borane and (SP)‐menthy‐loxy(o‐methoxyphenyl)phenylphosphine‐boranewas reductively cleaved at −78°C by lithium naphtha‐lenide or Li/NH3 with virtually net retention of configuration at phosphorus, providing secondary or tertiary phosphine‐boranes in excellent yields. New synthetic routes to optically pure C2‐symmetric bisphosphine‐boranes possessing chirality at phosphorus have been developed on the basis of these stereochemical studies.
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U2 - 10.1002/hc.520030519
DO - 10.1002/hc.520030519
M3 - Article
AN - SCOPUS:84986379473
VL - 3
SP - 563
EP - 575
JO - Heteroatom Chemistry
JF - Heteroatom Chemistry
SN - 1042-7163
IS - 5-6
ER -