Synthesis of chiral diferrocenyl dichalcogenides and their application to asymmetric nucleophilic ring opening of meso-epoxides
Synthesis of chiral diferrocenyl dichalcogenides and their application to asymmetric nucleophilic ring opening of meso-epoxides
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手性二茂铁基二硫属化物的合成及其在内消旋环氧化物不对称亲核开环中的应用
DOI：
10.1039/p19950002871
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
S. Uemura
中科院分区：
文献类型：
--
作者：
Y. Nishibayashi;J. Singh;S. Fukuzawa;S. Uemura
将市售的手性（1-二甲氨基乙基）二茂铁锂化，然后用单质硫或碲处理，再用空气氧化法制备了四种新型光学活性双[(R，S)-和（S，R）-2-（1-二甲氨基乙基）二茂铁]二硫族化合物[缩写为（R，S）-和（S，R）-(Fc*E)2(E = S和Te)]，每一种都具有两个轴向和两个中心手性元素，分离收率为42-65%。用x射线晶体学对二（S，R）-二茂铁二硫化物的结构进行了表征。用LiAlH4在四氢呋喃中还原上述（Fc*E）2和已知的（Fc*Se）2所产生的二茂铁基硫族阴离子（Fc*E -）被发现是有用的立体选择性亲核试剂，可使环氧环己烯、环氧环戊烯、环氧环烯和环氧顺式二苯乙烯等中位环氧化合物开环，以高收率得到相应的二茂铁基β-羟基烷基硫族化合物，其非对映异构体过量（de）高达71%。虽然非对映选择性取决于硫原子与中环氧化物的结合，但E = S和Se的非对映选择性一般高于E = Te。环氧环己烯与（S，R）-(Fc*Se)2开环反应得到（S，R）-2-（1-二甲氨基乙基）二茂铁基2-羟基环己基硒化物（66% de），并与（S，R）-(Fc*Se)2消去，得到ee为60%的(S)-环己烯醇。s构型表明，考虑到环氧化物、1-二甲氨基乙基和二茂铁之间的相互作用，手性二茂铁阴离子对环氧化物碳的亲核攻击导致的开环主要发生在阻碍最小的过渡态上。
Four novel optically active bis[(R,S)- and (S,R)-2-(1-dimethylaminoethyl)ferrocenyl] dichalcogenides [abbreviated as (R,S)- and (S,R)-(Fc*E)2(E = S and Te)], each of which possesses two axial and two central elements of chirality, have been prepared by lithiation of commercially available chiral (1-dimethylaminoethyl)ferrocenes, followed by treatment with elemental sulfur or tellurium and air oxidation, in 42–65% isolated yields. The structure of the di-(S,R)-ferrocenyl disulfide has been fully characterized by X-ray crystallography. Ferrocenyl chalcogenide anions (Fc*E–) produced by reduction of the above (Fc*E)2 and the known (Fc*Se)2 with LiAlH4 in tetrahydrofuran are found to act as useful stereoselective nucleophiles for ring opening of meso-epoxides such as cyclohexene oxide, cyclopentene oxide, cyclooctene oxide and cis-stilbene oxide to give the corresponding ferrocenyl β-hydroxyalkyl chalcogenides in high yields with up to 71% diastereoisomeric excess (de). Although the diastereoselectivity depends on the combination of chalcogen atom and meso-epoxide, it is generally higher with E = S and Se than with E = Te. Selenoxide elimination of (S,R)-2-(1-dimethylaminoethyl)ferrocenyl 2-hydroxycyclohexyl selenide (66% de), obtained by the ring opening of cyclohexene oxide with (S,R)-(Fc*Se)2, gives (S)-cyclohex-2-enol with 60% ee. The S-configuration suggests that the ring opening, by the nucleophilic attack of the chiral ferrocenyl chalcogenide anion on the epoxide carbon, mainly occurs via the least hindered transition state considering the interactions between the epoxide, the 1-dimethylaminoethyl moiety and the ferrocene.
影响因子：
3.6
作者：
NISHIBAYASHI, Y;SINGH, JD;UEMURA, S
通讯作者：
UEMURA, S