Selenium-stabilized carbanions. Synthesis of enals and silyl enones using 1,3-bis(phenylseleno)propene
Selenium-stabilized carbanions. Synthesis of enals and silyl enones using 1,3-bis(phenylseleno)propene
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硒稳定的碳负离子。
DOI：
10.1021/jo00348a002
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发表时间：
1982
影响因子：
3.6
通讯作者：
W. W. Willis
中科院分区：
文献类型：
--
作者：
H. Reich;M. C. Clark;W. W. Willis
考察了1，3-双(苯基硒)丙烯(4)作为具有n3(1)或n4和n3(3)反应性的丙烯合成子的用途。4与二异丙胺锂在-78℃的四氢呋喃中进行去质子化反应，得到一种锂试剂，该试剂与烷基卤化物(异戊基溴、2-溴丁烷)、环氧化物(环氧丙烷、环己烷)、羰基化合物(异丁醛、丙酮、4-叔丁基环己酮、3-戊酮)和三甲基硅氯反应顺利。用4当量的过氧化氢在二氯甲烷中氧化，产物以71-88%的产率顺利地转化为3-取代苯丙醇衍生物。与丙酮的反应产物也被还原消除，生成L-(苯基硒)-4-甲基-L，3-戊二烯。3-(三甲基硅基)-L，3-二(苯基硒)丙烯用二乙胺锂去质子化得到了一种可以烷基化(2-溴丙烷、2-溴丁烷、2-甲基-L-溴丙烷)和羟烷基化(丙酮)的试剂，具有很好的区域选择性。这些产物(7)用过氧乙酸氧化得到3-取代的L-(三甲基硅基)丙烯(8，乙烯基硅基酮)。与其他合成的等效试剂相比，4和6制备的阴离子表现出特殊的亲核性，并且丙烯部分的掩蔽可以在异常温和的条件下完成。
The utility of 1, 3-bis (phenylseleno) propene (4) as a propenone synthon having n3 (1) or n4 and n3 (3) reactivity has been examined. Deprotonation of 4 with lithium diisopropylamide in THF at-78 C proceeds to give a lithium reagent which reacts smoothly with alkyl halides (isopentyl bromide, 2-bromobutane), epoxides (propylene oxide, cyclohexene oxide), carbonyl compounds (isobutyraldehyde, acetone, 4-tert-butylcyclohexanone, 3-pentanone), and trimethylsilyl chloride. The products are smoothly converted to 3-substituted propenal derivatives in 71-88% yield by oxidation with 4 equiv of hydrogen peroxide in dichloromethane. The reaction product with acetone has also been converted to l-(phenylseleno)-4-methyl-l, 3-pentadiene by reductive elimination of the groups PhSeOH. Deprotonation of 3-(trimethylsilyl)-l, 3-bis (phenylseleno) propene with lithium diethylamide gives a reagent which can be alkylated (2-bromopropane, 2-bromobutane, 2-methyl-l-bromopropane) and hydroxyalkylated (acetone) with good regioselectivity. Oxidation of these products (7) with peracetic acid gives 3-substituted l-(tri-methylsilyl) propenones (8, vinyl silyl ketones). The anions preparedfrom 4 and 6 show exceptionalnucleophilicity compared to other synthetically equivalent reagents, and the unmasking of the propenone moiety can be ac-complished under unusuallymild conditions.