Studies on Wittig rearrangement of furfuryl ethers in steroidal side chain synthesis
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چکیده
Wittig rearrangement of 17(20)-ethylidene-16-furfuryloxy steroids 5–8 was examined. Reaction of 17E(20)-ethylidene-16afurfuryloxy steroid 5 with t-BuLi in THF afforded (20S,22S)and (20S,22R)-22-hydroxy steroids 9, 10 and 17Z(20)-ethylidene-16a-(2furyl)hydroxymethyl steroid 11 in 61, 28, and 9% yields, respectively. Base treatment of 17E(20)-ethylidene-16b-furfuryloxy steroid 7 gave (20R,22R)-22-hydroxy steroid 13 and 17Z(20)-ethylidene-16b-(2-furyl) hydroxymethyl steroid 14 in 60 and 17% yields. In contrast, 17Z(20)-ethylidene-16-furfuryloxy steroids 6, 8 led to the corresponding 2,3-rearranged products in low yields (25% for (20R,22S)-22hydroxy steroid 12; 31% for (20S,22R)-22-hydroxy steroid 10). Both (20S,22S)and (20S,22R)-22-hydroxy steroids 9, 10 were converted by catalytic hydrogenation into known compounds 16, 17, key intermediates for the synthesis of biologically active steroids. q 2004 Elsevier Ltd. All rights reserved.
منابع مشابه
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تاریخ انتشار 2005