Concerted Catalytic Reactions for Conversion of Ketones or Enol Acetates to Chiral Acetates
作者:Hyun M. Jung、Jeong H. Koh、Mahn-Joo Kim、Jaiwook Park
DOI:10.1021/ol9914043
日期:2000.2.1
[reaction: see text] Enol acetates or ketones asymmetrically transformed to chiral acetates in high yields with high optical purities through multistep reactions catalyzed by a lipase and a ruthenium complex. 2,6-Dimethylheptan-4-ol was chosen as a suitable hydrogen donor, and 4-chlorophenyl acetate was used as an acyl donor for the conversion of ketones.
The bonding isomers of triorganostannyl enolates were analyzed by 119Sn NMR spectroscopy. In some cases the existence of an equilibrium between the O-stannyl enolate and C-stannyl derivative was confirmed by variable temperature 119Sn NMR spectra.
Process for the preparation of crystalline vinylaromatic polymers with a predominantly syndiotactic structure
申请人:ENICHEM S.p.A.
公开号:EP0751154A1
公开(公告)日:1997-01-02
Process for the preparation of crystalline vinylaromatic polymers with a predominantly syndiotactic structure which comprises polymerizing the vinylaromatic monomers in the presence of a catalytic system consisting essentially of:
a) a complex of titanium having the formula (I):
Ti(OCONRR')n (I)
wherein R and R', the same or different, represent a C1-C12 aliphatic radical or C6-C12 aromatic radical whereas n is an integer equal to 3 or 4;
b) a cocatalyst selected from aluminoxane and a compound of boron having formula (II):
BX1X2X3 (II)
wherein X1, X2 and X3, the same or different, represent a C1-C20 perfluorinated hydrocarbon radical.
制备主要具有辛二烯结构的结晶乙烯基芳香族聚合物的工艺,包括在催化系统存在下聚合乙烯基芳香族单体,该催化系统主要由以下部分组成:
a) 具有式 (I) 的钛络合物:
Ti(OCONRR')n (I)
其中 R 和 R'(相同或不同)代表 C1-C12 脂肪族基或 C6-C12 芳香族基,而 n 是等于 3 或 4 的整数;
b) 选自氧化铝和具有式 (II) 的硼化合物的助催化剂:
BX1X2X3 (II)
其中相同或不同的 X1、X2 和 X3 代表 C1-C20 全氟烃基。
Process for the preparation of crystalline vinylaromatic polymers with a predominant syndiotactic structure
申请人:ENICHEM S.p.A.
公开号:EP0796875A2
公开(公告)日:1997-09-24
Process for the preparation of crystalline vinylaromatic polymers with a predominant syndiotactic structure which involves polymerizing vinylaromatic monomers in the presence of a catalytic system comprising:
a titanium complex having general formula (I):
wherein R1, R2, R3 and R4, the same or different, represent a hydrogen atom or a C1-C20 alkyl radical or a C6-C20 arylalkyl or aryl radical, on the condition that at least one of these is different from hydrogen.
Process for the production of vinyl-aromatic polymers with a high degree of syndiotacticity
申请人:ENICHEM S.p.A.
公开号:EP0838481A1
公开(公告)日:1998-04-29
Process for the preparation of crystalline vinylaromatic polymers with a high degree of syndiotacticity which comprises polymerizing vinylaromatic monomers in the presence of a catalytic system essentially consisting of:
a) a complex of titanium selected from those having the general formula:
(CpR1R2R3R4R5)TiX3 (I)
wherein the groups R1, R2, R3, R4 and R5 represent a hydrogen atom or C1-C10 alkyl groups;
X represents a hydrogen atom, a halogen such as chlorine, a C1-C10 alkyl or oxyalkyl radical or a C6-C12 oxyaryl radical;
b) an alkylaluminoxane; and
c) an organic derivative of tin;
characterized in that the alkylaluminoxane is methylaluminoxane (MAO) treated at 20-80°C under vacuum for 1-100 hours and the organic derivative of tin is tin tetraphenyl.
制备具有高度联合活泼性的结晶乙烯基芳香族聚合物的工艺,包括在催化系统存在下聚合乙烯基芳香族单体,该催化系统主要由以下部分组成:
a) 钛络合物,选自通式如下的钛络合物
(CpR1R2R3R4R5)TiX3 (I)
其中基团 R1、R2、R3、R4 和 R5 代表氢原子或 C1-C10 烷基;
X 代表氢原子、卤素(如氯)、C1-C10 烷基或氧烷基或 C6-C12 氧芳基;
b) 烷基铝氧烷;以及
c) 锡的有机衍生物;
其特征在于烷基铝氧烷是在 20-80°C 真空条件下处理 1-100 小时的甲基铝氧烷 (MAO),锡的有机衍生物是四苯基锡。