Enumeration of isomers of alkylcyclobutadienes by means of alkyl 1,1,1-triradicals

Abstract

Previous studies have shown that alkyl 1,1-biradicals could be used to enumerate the constitutional isomers of alkenes [1] and cyclopropanes [2]. In this study, an algorithm of using alkyl 1,1,1-triradicals to enumerate the constitutional isomers of alkylcyclobutadienes is described. An alkylcyclobutadiene molecule is considered to be formed by four alkyl 1,1,1-triradicals by pairing two of the electrons with two of the adjacent alkyl 1,1,1-triradicals, and the remaining unpaired electron with one of the other adjacent alkyl 1,1,1-triradical. This enumeration algorithm showed that the constitutional isomers of the methanol series enumerated by Henze and Blair [3] can be used for enumerating the constitutional isomer of unsaturated cyclic compounds.