Mass spectrometric studies on 4-aryl-1-cyclopropyl-1,2-dihydropyridinyl derivatives: an examination of a novel fragmentation pathway |
| |
Authors: | Bissel Philippe Geherin Skye Igarashi Kazuo Gandour Richard D Lazar Iulia M Castagnoli Neal |
| |
Institution: | Department of Chemistry, Virginia Tech, Blacksburg, VA 24061-0212, USA. |
| |
Abstract: | Examination of the electrospray ionization product ion spectra of 1,2-dihydropyridinyl and 4-aryl-1,2-dihydropyridinyl derivatives bearing a 1-cyclopropyl or 1-trans-2-phenylcyclopropyl group has led to the characterization of unexpected fragment ions. For example, the base peak at m/z 156 present in the product ion spectrum of trans-1-(2-phenylcyclopropyl)-4-phenyl-1,2-dihydropyridine proved not to be the expected 4-phenylpyridinium species but rather the isomeric 3-phenyl-5-azoniafulvenyl species. The results of studies with a series of structural and isotopically labeled analogs require a novel fragmentation pathway to account for the formation of this and related fragment ions. One possible pathway is based on an initial 1,5-sigmatropic shift of a cyclopropylmethylene hydrogen atom that is accompanied by opening of the cyclopropyl ring. The resulting eniminium intermediates then fragment to yield the 5-azoniafulvenyl species. |
| |
Keywords: | 1‐cyclopropyl‐4‐aryl‐1 2‐dihydropyridines fragmentation mechanism 5‐azoniafulvenyl species stable isotopes 1 5‐sigmatropic hydrogen migration |
本文献已被 PubMed 等数据库收录! |
|