The Wolff Rearrangement and 1,3-Dipolar Cycloaddition of 2-Diazo-3,4-bis(diphenylmethylene)cyclobutanone

Abstract

The first example of the Wolff rearrangement of α-diazocyclobutanone, the title diazo ketone (2), into the three-membered cyclic ketene (4) was observed. The ketene intermediate (4) could be trapped by its reaction with alcohols, aniline, azobenzene, and N-benzylideneaniline to afford 1-alkoxycarbonyl- (5a–c) and 1-phenylcarbamoyl-2,3-bis(diphenylmethylene)cyclopropane (5e), and 1,2-bis(diphenylmethylene)-5,6-diphenyl-5,6-diaza-(9) and 1,2-bis(diphenylmethylene)-5,6-diphenyl-5-azaspiro[2,3]hexan-4-one (10a), respectively. In contrast to the rearrangement, 2 directly reacted with p-benzoquinone and nitrosobenzene, affording the corresponding 1,3-dipolar cycloadducts (14 and 15).

Synthesis of Methylene- and Alkylidenecyclopropane Derivatives

“…Irradiation in the presence of imines or azobenzene produces the ketene adducts 122 and 123, respectively (Scheme 36). 164…”

“…Finally, thermolytic group eliminations have also been carried out successfully in some cases. 164,380 This broad compatibility has allowed long reaction sequences to be carried out on MCP and ACP derivatives in order to assemble the desired reactive functionalities attached to the cyclopropylidene system, as exemplified by recent work from Motherwell's 180,182,294c (Scheme 143) and Kilburn's 360, 364,435 (Scheme 144) groups, who used the synthesized ACPs for intramolecular transition metal-catalyzed [3 + 2] cycloadditions and radical cascade ring-closure reactions, respectively.…”

“…Irradiation of a 2-diazo-3,4-bis(diphenylmethylene)cyclobutanone ( 119 ) in water, alcohols or aniline as solvents produced the bis(diphenylmethylene)cyclopropanes 121 in good yields through a ketene species 120 . Irradiation in the presence of imines or azobenzene produces the ketene adducts 122 and 123 , respectively (Scheme ) 36 …”

“…Functional group interconversions aside from the cyclopropane ring, e.g., mesylation, tosylation, 5d,, nucleophilic substitutions of halides and sulfonates, , Wittig and related reactions, esterification, ,312a, thioesterification, 5a,,14a,c,, and amidation 441 of carboxylic acid or chlorides, usually occur without any inconvenient. Finally, thermolytic group eliminations have also been carried out successfully in some cases. ,

143

144

…”

Chemie thermisch und photochemisch erzeugter Cyclobutan‐ und Cyclobutenylidene

“…Suspensionen der Na-Sake von [10][11][12] Aus den obigen Ergebnissen mu0 geschlossen werden, d d der Zugang zu Cyclobutenylidenen und damit die Synthese von Spirohexadienen und -hexenen iiber Carbenzwischenstufen nur dann erfolgreich sein kann, wenn die Aktivierungsenergie der Ringoffnung erheblich grO8er ist als die der Carbenerzeugung. Die gleiche thermische und photochemische Ringoffnung von Cyclobutenon und seinen Derivaten ist beschriebenls).…”