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IV. Ketonitrones

  • Page ID
    24555
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    The ketonitrone 39 undergoes radical cyclization when treated with excess SmI2 (Scheme 11).47 This reaction is similar to that shown in Scheme 9 for a related ketooxime. Both reactions depend upon electron transfer from SmI2, and each produces a new five-membered ring. These reactions are stereo­selective but their selectivity is controlled in different ways. In the reaction of the ketonitrone, samarium remains coordinated with the oxygen atoms in the two devel­oping substituent groups during reaction. This coor­din­ation insures the stereo­selective formation of a cyclopentane ring in which the OH and N(OH)Bn groups are cis-related (Scheme 11). Since similar coor­din­ation does not occur during ketooxime reaction (Scheme 9), the emerging OH and NHOBn groups are not held on the same side of the ring; in fact, due to the steric size of the groups attached to the bonding carbon atoms in the radical 31, OH and NHOBn groups become trans-related in the product 32.

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    This page titled IV. Ketonitrones is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Roger W. Binkley and Edith R. Binkley.

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