Total synthesis of ionophores. 6. Asymmetric induction in the permanganate-promoted oxidative cyclization of 1,5-dienes

Abstract

We and others have demonstrated the utility of the permanganate-promoted oxidative cyclization of 1,5-dienes for synthesis of structural fragments found in oxygenated natural productsla'b•2 and materials of medicinal importance.3 In the standard implementation of this reaction, a structurally complex product possessing four new tetrahedral stereocenters is created stereospecifically from a simple achiral diene precursor in a single transformation. Of course under these circumstances racemic

A General Oxidative Cyclization of 1,5‐Dienes Using Catalytic Osmium Tetroxide

“…Our next objective was to search for methods of making these products enantiomerically pure 8. We turned our attention to the role of stereodirecting groups on the diene backbone, between the two alkene groups: this is the first time that this possibility has been explored.…”

Asymmetric Permanganate-Promoted Oxidative Cyclization of 1,5-Dienes by Using Chiral Phase-Transfer Catalysis This work was supported by the EPSRC (J.F.K.) and the Royal Society (R.C.D.B.). We thank Dr. Barry Lygo (University of Nottingham) for helpful discussions, and Syngenta and Merck Sharp and Dohme for unrestricted grants.

“…The same transformation has been carried out using other metal–oxo reagents and catalysts 7, 8. In the permanganate‐promoted oxidative cyclization reaction, control of absolute stereochemistry has been achieved with chiral auxiliaries;4a,4b however, preparation of enantiomerically enriched THF diols by oxidative cyclizations of achiral 1,5‐dienes has not been reported. Herein we report the novel high‐yielding phase‐transfer permanganate‐promoted oxidation of geranyl benzoate ( 1 ) to the corresponding THF diol 2 (Scheme ), and a procedure for the asymmetric oxidative cyclization of phenone dienes to produce enantiomerically enriched THF diols.…”

Oxidative cyclization in the synthesis of 5‐ and 6‐membered N,O‐heterocycles

“…This cyclization has also been effected with KMnO 4 [200] and recently by phase-transfer conditions, as an oxidation variant, with this reagent [201]. The syntheses of cis-solamin and its diastereoisomer have been recently described [202].…”

“…It has been mentioned earlier (see, Schemes 70 and 72) that 1,5-and 1,6-dienes undergo oxidative cyclization to substituted THF and THP rings. This cyclization has also been effected with KMnO 4 [200] and recently by phase-transfer conditions, as an oxidation variant, with this reagent [201]. The syntheses of cis-solamin and its diastereoisomer have been recently described [202].…”