87957-43-5Relevant articles and documents
Synthesis and Addition Reactions of 2-Phenyl-1-cyclopropene-1-carboxylates
Norden, Wolfgang,Sander, Volker,Weyerstahl, Peter
, p. 3097 - 3111 (2007/10/02)
From the olefins 1, 2, and 4 - 7 the 1-chloro-1-cyclopropanecarboxylic acids 15 - 20 are prepareded via the dichlorocyclopropanes 8, 9, and 11 - 14.The trans-isomers 15a - 20a were readily separated.Spiropentane 10 undergoes anionic ring cleavage with BuLi to give finally the ester 33.The tert-butyl esters 21 - 26 yield with KOtBu the cyclopropene esters 27 - 32.The trans-esters 21a - 26a react much faster than the cis-esters b.At C-3 unsubstituted chlorocyclopropane esters, e.g. 34, do not give stable cyclopropene esters even with lithium dialkylamides.Diazomethane adds to the esters 27 - 32 to give the pyrazolines 38 - 43, their isomers a and b being separable.With traces of base the bicyclic pyrazolines are cleaved to 1,4-dihydropyridazines 44 - 46.Cyclopropenes 27 - 30 react with thiophenolate to form the isomeric products 47 - 50; malonate adds to 28 and 31 to give 51, 52.With malononitrile via subsequent reactions the cyclopentadienes 55 - 57 are obtained.