Cyclooctanone 2- cyclobutanone

Halobutyl)cyclobutanones form cyclooctanones when they are reduced with tributyltin hydride in the presence of 2,2 -azobisisobutyronitrile.3,5 216, 217 Iodides usually give better yields than bromides. It is essential to add the tin hydride reagent slowly over a period of several hours, to keep its concentration low and thus avoid side reactions. Examples are the reactions to give l,s 2,3 and 3.217 A further example is found in ref 216. 

The enolate ions of ketones have become the most widely studied nucleophiles in SrnI reactions [21-23,40,66]. The enolate ions of acyclic and cyclic ketones (from cyclobutanone to cyclooctanone) [21,40] react with aryl and heteroaryl halides to afford the a-arylation products. No... 

Indeed, cyclobutanones constitute challenging synthetic intermediates for a whole host of applications including cyclopentanone, cyclohexanone and cyclooctanone formation, olefin and diene synthesis, geminal alkylation, reductive acylation, among others,... (vide infra). 

Another common strategy for construction of fused cyclooctanones is to first build a fused cyclobutanone by [2 + 2] cycloaddition of a vinylketene to a cycloalkene. Equation (58) illustrates this approach with Paquette s synthesis of the tricyclic skeleton of the ophiobolins. Cyclobutanone (108) is assembled by addition of a vinylketene to cyclopentadiene. Cyclopentenyllithium then adds to the less-hindered face of (108), and the lithium alkoxide undergoes a spontaneous anionic oxy-Cope rearrangement to afford the central cyclooctane ring. 

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