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Pyrido‐Annulated 1,3‐Azaphospholes: Synthesis of 1,3‐Azaphospholo[5,4‐ b ]pyridines and Preliminary Reactivity Studies
Author(s) -
Adam Mohamed Shaker S.,
Jones Peter G.,
Heinicke Joachim W.
Publication year - 2010
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201000253
Subject(s) - chemistry , reactivity (psychology) , medicinal chemistry , pyridine , hydrogen bond , crystal structure , stereochemistry , molecule , organic chemistry , medicine , alternative medicine , pathology
Pyrido‐annulated σ 2 ‐phosphorus heterocycles, 1,3‐azaphospholo[5,4‐ b ]pyridines 4 and 5 , were synthesized by reduction of diethyl 2‐aminopyridine‐3‐phosphonates 1 with LiAlH 4 and cyclocondensation of the resulting 2‐amino‐3‐phosphanylpyridines 2 with dimethylformamide and dimethylacetamide dimethyl acetal, respectively, via intermediate phosphaalkenes 3 . The P=C–N heterocycles are stable in the presence of OH and NH compounds but add t BuLi at the P=C bond. Reaction with one equivalent of M(CO) 5 (thf) leadsto η 1 ‐P‐coordinated (azaphospholo[5,4‐ b ]pyridine)M(CO) 5 complexes (M = Cr, Mo, W). Spectroscopic data are in accordance with the dominance of π‐acceptor properties. X‐ray crystal structure analyses reveal “base‐pairing” of 2‐amino‐3‐phosphanylpyridine ( 2a ) and NH‐functional azaphospholopyridine 5a by N–H ··· N hydrogen bonds, and the competing formation of 1,3‐diphosphetane 6c from the phosphaalkene intermediate.