Acid-promoted reaction of cyclic allylic diols with carbonyl compounds. Stereoselective ring-enlarging tetrahydrofuran annulations

Abstract:

Results Preparation of Cyclic Allylic Diols. The 1-alkenyl-1, 2-cycloalkanediol starting materials are readily prepared, although nonstereoselectively, from the reaction of an excess of a vinyllithium or vinyl Grignard reagent with a 2-hydroxycycloalkanone. The latter materials either are available commercially or are directly prepared from diesters by acyloin cyclization. 5 Alter-natively, the trans-diol stereoisomers are expediently prepared with complete stereocontrol by (acyloxy) borohydride reduction6 of 2-alkenyl-2-hydroxycycloalkanones. 7 In the cyclopentyl series,(3)(a) For our initial report, see: Herrinton, P. M.; Hopkins, M. H.; Mishra, P.; Brown, M. J.; Overman, L. E. J. Org. Chem. 1987, 52, 3711.(b) Part of this work is also briefly reported in: Overman, L. E. In Selectivities in Lewis-Acid Promoted Reactions; NATO ASI Series; Schinzer, D., Ed.; Kluwer: Dordrecht, The Netherlands, 1989; Vol. 289, p 1.(4) For a brief …

Año de publicación:

1991

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