Cobalt-Catalyzed Intramolecular Silylperoxidation of Unsaturated Diisopropylsilyl Ethers

Abstract

A cobalt-catalyzed intramolecular silylperoxidation reaction was developed that allows for the conversion of unsaturated diisopropylsilyl ethers to 3-sila-1,2,4-trioxepanes. Reduction of the peroxide unit of the 3-sila-1,2,4-trioxepane yields six-membered ring diisopropylsilylene acetals.

Tethered Silanoxymercuration of Allylic Alcohols

“…18,19 There is one example from the Lee laboratory of the use of silanols for gold-catalyzed alkyne functionalization 20 and an example of a silylperoxidation reaction of homoallylic alcohols from the Woerpel laboratory. 21 Nevertheless, our survey of the literature revealed no examples of the silanol tether employed in alkene functionalization. Our work has been directly inspired by the pioneering contributions of Overman 22,23 and Leighton, 24−28 who demonstrated that acetal tethers could be used for the mercuric salt-mediated functionalization of olefins (Scheme 1).…”

“…The resulting cyclic silanediol compounds, reminiscent of intermediates en route to polyol natural products (Figure ), − are synthons for a variety of further transformations. Silanol auxiliaries have been popularized by Gevorgyan and co-workers as directing groups in C–H functionalization reactions. , There is one example from the Lee laboratory of the use of silanols for gold-catalyzed alkyne functionalization and an example of a silylperoxidation reaction of homoallylic alcohols from the Woerpel laboratory . Nevertheless, our survey of the literature revealed no examples of the silanol tether employed in alkene functionalization.…”

Tethered Silanoxyiodination of Alkenes

“…Tethered alkene functionalization reactions allow the synthetic chemist to transform olefins with unusual precision. − Because of the predisposition for six- and seven-membered cyclic transition states, one can simply count the number of atoms from the nucleophilic auxiliary (“the tether”) where the functionalization event is likely to take place; due to geometric constraints, these reactions generally proceed with high regio- and diastereoselectivity. Our laboratory is deeply invested in developing tethered olefin functionalization reactions, and we have disclosed such reactions using sulfamate, , phosphoramidate, and di- tert -butylsilanoxy tethers. , …”

Tethered Silanoxyiodination of Alkenes

“…Tethered alkene functionalization reactions allow the synthetic chemist to transform olefins with unusual precision. [1][2][3][4][5][6][7] Because of the predisposition for six-and sevenmembered cyclic transition states, one can simply count the number of atoms from the nucleophilic auxiliary ("the tether") where the functionalization event is likely to take place; due to geometric constraints, these reactions generally proceed with high regio-and diastereoselectivity. Our laboratory is deeply invested in developing tethered olefin functionalization reactions, and we have disclosed such reactions using sulfamate, 8,9 phosphoramidate, 10 and di-tert-butyl-silanoxy tethers.…”