Enantioselective cyanosilylation of aldehydes catalyzed by novel camphor derived Schiff bases-titanium(IV) complexes
作者:Ewelina Błocka、Mariusz J. Bosiak、Mirosław Wełniak、Agnieszka Ludwiczak、Andrzej Wojtczak
DOI:10.1016/j.tetasy.2014.03.001
日期:2014.4
Five tridentate Schiff bases have been prepared from (1R,2S,3R,4S)-3-amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol and salicylaldehydes. X-ray structure investigation revealed differences in their molecular conformation, and their titanium(IV) complexes have been studied with NMR techniques. Among them the complex with the Schiffbase obtained from 2-hydroxy-3-isopropylbenzaldehyde, is the most selective
The enantioselective addition of trimethylsilyl cyanide to a variety of aldehydes proceeded by the aid of a catalyst prepared in situ from titanium tetraisopropoxide [Ti(O-i-Pr)4] and chiral Schiff bases and gave the corresponding cyanohydrins in high optical yield (up to 96% e.e.). A remarkable rate enhancement was brought about by the addition of the Schiffbase to the titanium alkoxide mediated
The β-amino alcohol 1b−Ti(Oi-Pr)4 complex has been shown to catalyze the enantioselective cyanosilylation of aldehydes efficiently. In the presence of 5 mol % of 1b−Ti(Oi-Pr)4 complex catalyst, the aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were converted to their corresponding trimethylsilyl ethers of cyanohydrins in 90−99% yields with up to 94% ee under mild conditions.
β-氨基醇1b -Ti(O i -Pr)4配合物已显示出可有效催化醛的对映选择性氰基硅烷化反应。在5摩尔%的1b -Ti(O i -Pr)4络合催化剂存在下,芳族,共轭,杂芳族和脂族醛以90-99%的产率转化为相应的氰醇三甲基甲硅烷基醚,产率最高为94 %ee在温和条件下。
Chiral Metal–Organic Framework Decorated with TEMPO Radicals for Sequential Oxidation/Asymmetric Cyanation Catalysis
作者:Zijian Li、Yan Liu、Xing Kang、Yong Cui
DOI:10.1021/acs.inorgchem.8b01630
日期:2018.8.20
cocrystallizing achiral (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-substituted tricarboxylate and enantiopure VO(salen)-derived dipyridine ligands. The chiral MOF can function as an efficient heterogeneous catalyst for the sequential alcoholoxidation/asymmetric cyanation of aldehyde reactions with enhanced activity and enantioselectivity compared to the homogeneous counterpart.
CYANATION CATALYST AND METHOD FOR PRODUCING OPTICALLY ACTIVE CYANHYDRIN COMPOUND USING THE SAME
申请人:Ohkuma Takeshi
公开号:US20100029977A1
公开(公告)日:2010-02-04
The present invention can provide a cyanation catalyst represented by the general formula (I):
(in the formula (I), R
1
through R
4
are each an optionally substituted hydrocarbon group; R
1
and R
2
and/or R
3
and R
4
may form an optionally substituted carbon chain ring; R
5
through R
8
are each a hydrogen atom, or an optionally substituted hydrocarbon group; R
5
and R
6
and/or R
7
and R
8
may form an optionally substituted carbon chain ring; R
9
and R
10
are each a hydrogen atom, or an optionally substituted hydrocarbon group; W, X and Y each represent an optionally substituted binding chain; X and/or Y may be non-existent; M represents a metal or a metal ion; and ligands of M may each be located at any position).