Photoreaction of D-nor-5.ALPHA.-androstan-16-one oxime, a steroidal cyclobutanone oxime.
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概要
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Irradiation of <I>D</I>-nor-5α-androstan-16-one oxime in methanol leads to a mixture of seco-nitriles; <I>D</I>-nor-13,16-seco-5α-androst-13(18)-ene-16-nitrile (<B>3</B>), <I>D</I>-nor-13,16-seco-5α-androst-12-ene-16-nitrile (<B>7</B>), 13ξ-methoxy-<I>D</I>-nor-13,16-seco-5α-androstane-16-nitrile (<B>8</B>), and 15-hydroxy-<I>D</I>)-nor-15,16-seco-5α-androstane-16-nitrile (<B>9</B>). These result from ionic α-fissions at either of the α-bonds. Low yields of three lactams, 17-aza-5α-androstan-16-one (<B>6</B>), 17-aza-5α,13α-androstan-16-one (<B>11</B>), and 16-aza-5α-androstan-17-one (<B>5</B>), resulting from photo-Beckmann rearrangement, are also formed. The formation of <B>11</B> is the second proven example of a photo-Beckmann rearrangement in which a chirality of the migrating carbon center is not retained in the product lactam and an intervention of a ring-opened intermediate must be involved. It was found that direction of the α-cleavage of this excited four-membered cyclic ketone oxime was not governed only by the stability of cleaved ions, since seco-nitrile <B>9</B> resulting from α-fission to a less stable primary carbonium ion was formed together with seco-nitriles <B>3</B>, <B>7</B>, and <B>8</B> from a more stable tertiary carbonium ion. The Beckmann rearrangement of the mixture of <I>syn</I> and <I>anti</I> oximes with thionyl chloride afforded the two expected lactams <B>5</B> and <B>6</B> together with the products of Beckmann fission <B>3</B> and <I>D</I>-nor-13,16-seco-5α-androst-13(14)-ene-16-nitrile resulting from a cleavage to tertiary carbonium ion.
- 公益社団法人 日本化学会の論文
著者
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Uchida Tsutomu
Department Of Applied Physics Faculty Of Engineering Hokkaido University
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Suginome Hiroshi
Department of Chemistry, Faculty of Science
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