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Diphosphanylketenimines: New Reagents for the Synthesis of Unique Phosphorus Heterocycles
Author(s) -
Ruiz Javier,
Marquínez Fernando,
Riera Víctor,
Vivanco Marilín,
GarcíaGranda Santiago,
Díaz M. Rosario
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020902)8:17<3872::aid-chem3872>3.0.co;2-0
Subject(s) - cycloaddition , chemistry , phosphole , ketenimine , medicinal chemistry , toluene , dimethyl acetylenedicarboxylate , dimer , organic chemistry , catalysis
Two consecutive [3+2] cycloaddition reactions of the diphosphanylketenimine (PPh 2 ) 2 CCNPh ( 3 ), involving the phosphanyl groups, with two equivalents of the electron‐poor alkynes dimethyl acetylenedicarboxylate or methyl acetylenecarboxylate give rise to the formation of the bicyclic 1 λ 5 ,3 λ 5 ‐diphospholes 5 a , b , which contain a phosphorane unit with five carbon substituents attached to the phosphorus center. Compound 3 undergoes cyclodimerization by crystallization, affording the unsymmetrical dimer 6 , which is converted back to 3 by heating in toluene. Compound 6 can be oxidized stepwise on the three trivalent phosphorus atoms by treatment with H 2 O 2 affording 7, 9 , and the transient species 10 , which are transformed into their corresponding ketenimine monomers either spontaneously ( 10 ) or by heating in toluene ( 7, 9 ). In this way, the compound (OPPh 2 )(PPh 2 )CCNPh ( 8 ) is quantitatively obtained. Compound 8 readily reacts with the alkynes MeO 2 CCCCO 2 Me and MeO 2 CCCH, and with phenyl isocyanate and ethyl isothiocyanate through regiospecific [3+2] cycloaddition processes furnishing several λ 5 ‐phosphole and λ 5 ‐azaphosphole derivatives. Finally, the reaction of 8 with N ‐methylpropargylamine yields the new 2,3‐dihydro‐1,4‐ λ 5 ‐azaphosphinine 15 through a cycloaddition process involving two functional groups from each molecule.