Preparation of 3,3-disubstituted cyclopropanes by the dehydrohalogenation of monohalocyclopropanes under phase transfer catalysis conditions

Synthesis of 1-alkynyl-2-dialkylaminocyclopropanes and 1-alkynyl-2-diazolylcyclopropanes by reactions of 1-alkynyl-1-chlorocyclopropanes with amines and their lithium derivatives

“…However, in the presence of a stronger base (KOH in DMSO) used earlier for the synthesis of cyclopropenes from chlorocyclopropanes, 19 1 alkynyl 1 chloro 2,2 dimethylcyclopropanes 1a-b react with pyrazole, 2,5 dimethylpyrazole, imidazole, and 2 methylimidazole to produce the corresponding 1 (alk 1 ynyl) 2 diazolylcyc lopropanes 7a-f in 23-72% yields (Scheme 5, Table 2). …”

Reaction of 1-(alk-1-ynyl)-1-halocyclopropanes with alcohols and phenol in KOH/DMSO as a method for the synthesis of 2-alkoxy-1-alkynyl- and 1-alkynyl-2-phenoxycyclopropanes

“…Note that the basic system KOH/DMSO has been earlier successfully used for obtaining cyclo propenes from halocyclopropanes. 5 Until now, the prin cipal methods for preparing 1 alkynyl 2 alkoxycyclo propanes were the addition of ethynylcarbenes, generated from the corresponding diazoalkynes or 3H pyrazoles, to vinyl ethers, 6,7 the intramolecular cyclization of 4 alkoxy 5 haloalk 1 ynes 8 and 4 alkoxy 5 tosyloxyalk 1 ynes 9 under action of strong bases, as well as the reaction of 2,2 dichloro 10 and 2,2 dibromovinylalkoxycyclopro panes 11 with organometallic compounds. 1 Alkynyl 2 alkoxycyclopropanes are polyfunctional synthons, which were introduced into the reactions of hydrogenation, 9 cross coupling at the triple bond, 12 and metallation at the methine hydrogen atom of the cyclopropane ring at the acetylene substituent, 8 as well as were successfully used in the synthesis of unsaturated polycyclic alcohols 8 and ketones.…”