2-Alkenyl anions and their surprising endo preference. Facile and extreme stereocontrol over carbon-carbon linking reactions with organometallics of the allyl type

On structural equilibration, butenyl sodium, potassium and cesium strongly favor the cis (endo) configuration over the extended form. The cis-trans ratios vary from 93:7 to 96:4 and 99.9:0.1 in the series Na, K, and Cs; the corresponding value for 2-butene is 23:77. Homologous alkenylmetal compds. exhibit less extreme stereoselectivities, but still follow the same trend. The metal effect on the endo-preference is due to the electropositivity and bulk of the metal as well as intramol. H bonding between the alkyl group attached to the inner side of the allyl moiety with the electron excess accumulated at the other allylic terminus. [on SciFinder (R)]


Published in:
Journal of the American Chemical Society, 98, 15, 4674-6
Year:
1976
Keywords:
Note:
CAN 85:159238 22-9 Physical Organic Chemistry Inst. Chim. Org.,Univ. Lausanne,Lausanne,Switz. Journal 0002-7863 written in English. 590-18-1; 624-64-6; 627-20-3; 646-04-8; 674-76-0; 690-08-4; 691-38-3; 762-63-0; 13950-06-6; 36306-56-6; 51760-91-9; 59304-73-3; 59304-74-4; 59304-75-5; 59304-76-6; 59304-77-7; 60647-26-9; 60647-27-0; 60647-28-1; 60647-29-2; 60647-30-5; 60647-31-6; 60647-32-7; 60647-33-8; 60647-34-9; 60647-35-0; 60647-36-1; 60647-37-2; 60647-38-3; 60647-39-4; 60647-40-7; 60647-41-8; 60647-42-9; 60647-43-0; 60647-44-1; 60647-45-2; 60647-46-3; 60647-47-4; 60647-48-5; 60647-49-6; 60647-50-9; 60647-51-0; 60647-52-1; 60647-53-2; 60647-54-3; 60647-55-4; 60647-56-5; 60647-57-6; 60647-58-7; 60684-51-7 Role: PRP (Properties) (isomerism of)
Laboratories:




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