Reactions of 2‐Pyridyl Substituted Phosphine Oxides and Phosphonium Salts with Organometallic Reagents and in Aqueous Media

Abstract

Phosphine oxides bearing two or three 2‐pyridyl groups react with organometallic reagents affording 2,2′‐bipyridyl, 2‐substituted pyridines and pyridine in good yields. Phosphonium salts and phosphine oxides, bearing at least two 2‐pyridyl or substituted 2‐pyridyl groups also give the corresponding 2,2′‐bipyridyls and pyridines upon treatment with acid or neutral solvents such as water and alcohols in substantial yields. The 2,2′‐bipyridyls are considered to be formed by ligand coupling within the pentacoordinated phosphorus intermediate formed incipiently during the reaction.

Reactions of heteroaryllithium compounds with phosphorus trichloride, phosphorus oxychloride, and thionyl chloride. Formation of heterocyclic biaryls

“…pyridyl in the reaction with 2-benzothiazyllithium or 2-pyridyllithium, respectively [ 1,3]. A similar coupling was also found in the reactions of phosphine oxides bearing two or three pyridyl groups with organometallic reagents [3,4].…”

“…A similar coupling was also found in the reactions of phosphine oxides bearing two or three pyridyl groups with organometallic reagents [3,4]. Also, many 2-pyridyl sulfoxides have been found to undergo ligand coupling by treatment with a Grignard reagent [5,6] or an organolithium reagent [6,7].…”

Quantum chemical studies on acidity-basicity behaviors of some bipyridine derivatives

“…It seems that the substituted bipyridine derivatives have been prepared mostly by reactions of Grignard reagents or organo-lithium derivatives with various sulfur and phosphor containing compounds respectively. [1][2][3][4][5][6][7][8][9] Studies on structure of bipyridine derivatives are also indicate an enormous amount of research affords. A low temperature X-ray structure, 10 the theoretical calculations [11][12][13][14][15] and spectroscopic studies of bipyridine derivatives have been reported in the literature.…”

Synthesis and Characterization of Alkyltris(2-pyridyl)phosphonium Salts

“…14). Uchida et al 11d,12,15,16 have previously reported in closely related systems the formation of bipyridines from (1) the reaction of 2-pyridylphosphines or 2-pyridylphosphine oxides and chlorine followed by slow hydrolysis in alcohol or water and (2) the slow reaction of pyridylphosphine oxides or 1d with H 2 O (CH 3 OH) or H 2 O(CH 3 OH)/HCl, respectively. In this work, the same authors proposed a reaction mechanism (Scheme 2 11d,16 ) that accounts for the formation of 2 and 3.…”