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Theoretical elucidation on the mechanism of 1H‐1,2,4‐diazaphospholes synthesis from 1,3‐bis (amino)‐2‐phosphaallyl chlorides with hydrazine
Author(s) -
Huo RuiPing,
Zhang Xiang,
Zhang CaiFeng
Publication year - 2019
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.3899
Subject(s) - chemistry , singlet state , hyperconjugation , hydrazine (antidepressant) , carbene , medicinal chemistry , solvent , reaction mechanism , decomposition , electron transfer , stereochemistry , photochemistry , organic chemistry , catalysis , molecule , excited state , physics , chromatography , nuclear physics
The mechanism of the reaction of 1,3‐bis (amino)‐2‐phosphaallyl chlorides with hydrazine for the synthesis of 1H‐1,2,4‐diazaphospholes in CHCl 3 solvent has been extensively investigated at the B3LYP/6‐311G (d, p) level. The reaction is initiated by the elimination of HCl and formation of a key intermediate A , then A subsequently undergoes H‐migration‐cyclization ( A → B ) and Me 2 NH elimination reactions ( B → C ) to afford carbene intermediate C , and C can transform to F along both single and triplet potential energy surfaces in three steps. H‐migration‐cyclization ( A → B ) step was identified as a proton‐coupled electron transfer (PCET) process, and singlet‐triplet PES crossing should be important in decomposition of C to D1 and D2 . For R═Me, Ph and H, the rate control step should be the decomposition of C , while for R═ t Bu, the first Me 2 NH removal step is the rate control one. Theoretical results suggested that t Bu is a preferable group than Ph, Me, and H in this reaction, which can be attributed to hyperconjugation effects of t Bu, showing good agreement with experimental data.