de Meijere, Armin; Kozhushkov, Sergei I.; Yufit, Dmitry S.; Boese, Roland; Haumann, Thomas; Pole, David L.; Sharma, Pradeep K.; Warkentin, John:

Cyclopropyl building blocks for organic synthesis. Part 36. Unprecedented addition of dialkoxy carbenes to tetrasubstituted alkenes: bicyclopropylidene and 2-chlorocyclopropylideneacetate.

In: Liebigs Annalen, (1996) ; Nr. 4, S. 601-612
ISSN: 0947-3440
Zeitschriftenaufsatz / Fach: Chemie
The cycloaddn. reactions of several dialkoxy carbenes generated in situ from the corresponding dialkoxyoxadiazolines of type I (R = R1 = alkyl) with bicyclopropylidene afford the dialkyl acetals of dispiro[]heptan-7-one (II), whereas the analog addn. to (1-chloromethylene-1-carboxylate)cyclopropane leads to the formation of a complex mixt. of products. Those products can best be rationalized in terms of nucleophilic attack of the dialkoxy carbene on the strained CC double bond, to form a dipolar intermediate capable of a variety of intramol. rearrangements. Several reactions of the compds. of type II are reported.