Allenyl cyclobutanol

In 2008, Cramer described a rhodium(I)-catalyzed enantioselective rearrangement of allenyl cyclobutanols (Scheme 10) [44]. The formation of rhodium(I)-aUcoxide 35 triggered a / -carbon elimination, providing the corresponding aUcyl-rhodium... 

Scheme 10 Enantioselective rhodium(I)-catalyzed rearrangement of allenyl cyclobutanols...

Matsumura, S. Maeda, Y. Nishimura, T. Uemura, S. Palladium-catalyzed asymmetric arylation, vinylation, and allenylation of tert-cyclobutanols via enantioselective C—C bond cleavage./. Am. Chem. Soc. 2003, 125, 8862-8869. 

Scheme 24 Enantioselective palladium-catalyzed ring expansion of allenyl tert-cyclobutanols...

Palladium(0)-catalyzed asymmetric arylation of tert-cyclobutanol 33 with bromobenzene, involving enantioselective C-C bond cleavage, furnished the chiral y-arylated ketone 34 (Scheme 3.13) [24]. Good enantioselectivity was observed when a chiral ferrocenyl P,N-ligand was used. y-Alkenylated and y-allenylated ketones were also obtained by asymmetric ring opening. 

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