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A Theoretical Investigation of Cycloadditions of Hydrogen Isocyanide to CH 2 X and PHX Dipolarophiles (X = CH 2 , NH, O, SiH 2 , PH, S)
Author(s) -
Nguyen Minh Tho,
Keer Annik Van,
Vanquickenborne Luc G.
Publication year - 1997
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19971300111
Subject(s) - chemistry , regioselectivity , cycloaddition , ab initio , isocyanide , molecular orbital , ab initio quantum chemistry methods , transition state , computational chemistry , stereochemistry , crystallography , molecule , organic chemistry , catalysis
We performed a systematic investigation of [2 + 1] cycloadditions of HNC to dipolarophiles of the type CH 2 X and PHX with XCH 2 , NH, O, SiH 2 , PH, and S, as well as HNNH and H 2 SiSiH 2 . Ab initio MO calculations at the QCISD(T)/6‐311G(d,p)/MP2/6‐31G(d,p)+ZPE level were applied to construct the minimum‐energy reaction pathways. Calculated results concerning the regiochemistry of the approaches and the stereochemistry of the product formation were analyzed in relation with established concepts such as frontier orbital, net charge distribution and stereoelectronic effect. For some systems, up to four distinct transition structures for cycloaddition were found. In general, there is a certain similarity between the behavior of both C and P series of dipolarophiles. The characteristics of the transition structures can be, in most cases, recovered by using qualitative concepts. The [2 + 1] cycloadditions are highly regioselective and stereospecific. Silicon‐containing dipolarophiles are particularly attractive as they exhibit very small energy barriers to addition to isocyanides.