The role of dianion coupling in the synthesis of dibenzylbutane lignans.
The role of dianion coupling in the synthesis of dibenzylbutane lignans.
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双阴离子偶联在二苄基丁烷木脂素合成中的作用。
DOI：
10.1021/np50080a006
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发表时间：
1992
影响因子：
5.1
通讯作者：
Fremont,SL
中科院分区：
文献类型：
--
作者：
Belletire,JL;Fry,DF;Fremont,SL
双阴离子偶联反应已用于制备外消旋形式的结构相关的木酚素天然产物。一种容易获得的碘代羧酸 10 已被用于单独的序列中以提供四氢呋喃木脂素 burseran [6] 和丁内酯木脂素 deoxypodorhizon [7]。 burseran 和 deoxypodorhizon 的关键策略涉及适当的二阴离子与 ot-iodo 羧酸盐 13 的反应。采用酸或碱下的平衡来产生 burseran 和 deoxypodorhizon 的取代的苄基侧链的反式立体化学。为了实现丙二阴离子反应性并避免在脱氧地黄合成过程中发生副反应，有必要开发酰基磺酰胺二阴离子的化学性质。作为进一步的结构证明，我们的合成脱氧地黄也被用作异牡丹烷 [8] 的成功序列中的底物，异牡丹烷是抗肿瘤原型 Steganacin [91] 的已知中继中间体。二价阴离子 (1)，无论是通过与亲电试剂 (2) 反应还是通过受控氧化 (3)，都是机械上有吸引力的 (4) 碳-碳键形成中间体 (5)。从合成实用性的角度来看，双阴离子的所有碳-碳成键反应都可以称为“双阴离子偶联”，并根据这些变体是否具有与偶联碳相连的相似或不同基团进一步细分。
Dianion coupling reactionshave been used to prepare structurally related lignan natural products in racemic form. A readily available-iodocarboxylic acid 10 has been employed in separatesequences to afford the tetrahydrofuran lignan burseran [6] and the butyrolactone lignan deoxypodorhizon [7]. The key strategy for both burseran and deoxypodorhizon involved reaction of the appropriatedianion with an ot-iodo carboxylate salt 13. Equilibration under acid or base was employed to create the trans stereochemistry of the substituted benzyl side chains of both burseran and deoxypodorhizon. To achieve properdianion reactivity and to avoid side reactions in the synthetic sequence to deoxypodorhizon, it was neces-sary to develop the chemistry of acylsulfonamide dianions. As a further structure proof, our syn-thetic deoxypodorhizon was also utilized as a substrate in a successful sequence to isostegane [8], a known relay intermediate to the antineoplastic prototype steganacin [91.Dianions (1), either by reaction with electrophiles (2) or via controlled oxidation (3), are mechanistically attractive (4) intermediates for carbon-carbon bond formation (5). From the perspective of synthetic utility, all carbon-carbon bond-making reactions of dianions can be termed “dianioncoupling” and further subclassified according to whether or not these variants have similar or different groupsattached to the coupling carbons.