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Cycloadducts from Diazocumulenes and 1,2,3(λ 3 )‐Diazaphospholes: Thermolysis Generates Products Derived from 3‐Alkenylidene‐1,2,3(λ 5 )‐diazaphospholes
Author(s) -
Kerth Jochen,
Maas Gerhard
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199910)1999:10<2633::aid-ejoc2633>3.0.co;2-i
Subject(s) - chemistry , dimethyl acetylenedicarboxylate , cycloaddition , thermal decomposition , silanes , diazo , medicinal chemistry , molecular nitrogen , yield (engineering) , phosphorane , organic chemistry , nitrogen , materials science , silane , metallurgy , catalysis
(1‐Diazo‐2‐oxoalkyl)silanes 1 react with 2‐acyl‐1,2,3(λ 3 )‐diazaphospholes 4 to form [3+2] cycloaddition products 5 , which indicate that 1‐diazo‐2‐silyloxy‐1‐alkenes 2 , coexisting with 1 as the minor equilibrium component, have been trapped. Thermal impact on cycloadducts 5 generates the tricyclic phosphorus heterocycles 9 ; their formation can be rationalized by two competing processes, namely thermal [3+2] cycloreversion into 2 and 4 , and extrusion of molecular nitrogen. The latter process is likely to generate 3‐alkenylidene‐1,2,3(λ 5 )‐diazaphospholes 8 , which are trapped intermolecularly by diazaphospholes 4 . Intermediates 8 could not be intercepted with dimethyl acetylenedicarboxylate (DMAD); rather, 5i reacts with DMAD to form the spiro‐λ 5 ‐phosphorane 11 in low yield.