84253-52-1Relevant academic research and scientific papers
Carbenes, 28. tert-Butyl 2,3,4-Tri-tert-butylcyclobutadiene-1-carboxylate
Eisenbarth, Philipp,Regitz, Manfred
, p. 3796 - 3810 (2007/10/02)
The cyclopropenyldiazoacetate 3a - available from tri-tert-butylcyclopropenylium bromide (1) and the mercury bis(diazoacetate) 2a - is the starting material for the synthesis of the title compound 5a.The carbene 4a, generated photolytically from 3a, is responsible for the formation of both the cyclobutadiene 5a and the acetylenes 6 and 7a.Acetylene formation is also observed in the flash pyrolysis of 3a (formation of 6, 7a, 8, and 9) and 5a (formation of 6, 8, and 9).The extremely air sensitive cyclobutadiene 5a ( -> 16) shows a pronounced cycloaddition behaviour towards dienophiles.With dimethyl ac etylenedicarboxylate, maleic anhydride, cyclopentadiene, diethyl azodicarboxylate and 4-phenyl-1,2,4-triazoline-3,5-dione cycloadducts were isolated (17, 18, 19, 20, 21).The series of the diazadihydro Dewar benzenes is also entered by the reaction of the cyclopropenyldiazoacetates 3 with the triazolinedione; the betaines 22 and 24 are regarded to be intermediates of this reaction.
