Swapped selectivities: The use of tailor‐made catalysts results in anomalous endo/exo selectivities and high enantioselectivities in the Diels–Alder reactions of cyclopentadiene with different acroleins (see scheme). These supramolecular catalysts are prepared in situ from chiral diols, arylboronic acid, and tris(pentafluorophenyl)borane, and can discriminate the re/si face of the dienophile as well
BBr3-chiral phosphoric acid complexes are highly effective and practical Lewis acid-assisted Brønsted acid (LBA) catalysts for promoting the enantioselective Diels-Alder (DA) reaction of α-substituted acroleins and α-CF3 acrylate. In particular, the DA reaction of α-substituted acroleins with 1,2-dihydropyridines gave the corresponding optically active isoquinuclidines with high enantioselectivities
Transition-Metal Aqua Complexes of 4,6-Dibenzofurandiyl-2,2‘-bis(4-phenyloxazoline). Effective Catalysis in Diels−Alder Reactions Showing Excellent Enantioselectivity, Extreme Chiral Amplification, and High Tolerance to Water, Alcohols, Amines, and Acids
作者:Shuji Kanemasa、Yoji Oderaotoshi、Shin-ichi Sakaguchi、Hidetoshi Yamamoto、Junji Tanaka、Eiji Wada、Dennis P. Curran
DOI:10.1021/ja973519c
日期:1998.4.1
from nickel(II) perchlorate hexahydrate has an octahedral structure with three aqua ligands, and it can be isolated and stored for months without loss of catalytic activity. Iron(II), cobalt(II), copper(II), and zinc(II) complexes are similarly active. The absoluteconfiguration induced in the reaction can be readily predicted on the basis of the C2-symmetric structure of the complexes as well as the
阳离子水配合物由反式螯合三齿配体 (R,R)-4,6-二苯并呋喃二基-2,2'-双(4-苯基恶唑啉) (DBFOX/Ph) 和各种过渡金属 (II) 制备高氯酸盐。这些配合物是环戊二烯与 3-烯酰基-2-恶唑烷酮亲二烯体的 Diels-Alder 反应的有效催化剂,并显示出优异的对映选择性。由六水合高氯酸镍 (II) 制备的活性催化剂配合物具有八面体结构和三个水配体,可以分离和储存数月而不会损失催化活性。铁 (II)、钴 (II)、铜 (II) 和锌 (II) 配合物具有类似的活性。根据配合物的 C2 对称结构以及底物配合物的简单结构,可以很容易地预测反应中诱导的绝对构型。由 Ni(II) 或 Zn(II) 高氯酸盐制备的水络合物在 Diels-Alder 反应中产生高效的手性放大。使用 DBFOX/Ph 配体...
Catalytic enantioselective Diels-Alder reactions using titanium complexes of cis-N-sulfonyl-2-amino-1-indanols
作者:E.J. Corey、Thomas D. Roper、Kazuaki Ishihara、Georgios Sarakinos
DOI:10.1016/s0040-4039(00)61343-6
日期:1993.1
A titaniumcomplex derived from (1R, 2S)-N-(2,4,6-trimethylbenzenesulfonyl)-2-amino-1-indanol catalyzes the Diels-Alder reaction of 2-bromoacrolein and cyclopentadiene with 96.5:3.5 enantioselectivity. A new and efficient synthesis of 2-amino-1-indanol (6) contributes to the potential of this methodology.
large rate differences on variation of the anion are all characteristics of the new Ru Lewisacid [CpRu((S,S)-biphop-F)]+ (biphop-F=(C6 F5 )2 POCH2 (Ph)CH2 (Ph)OP(C6 F5 )2 ). The structure of complex 1 (L=methacrolein, Y=SbF6 ) provides evidence for a cooperative binding of the dienophile by both the Lewisacid and the anion.
易产生,在室温下溶液中稳定,在Diels-Alder反应中具有高对映选择性,有效的催化剂回收率以及阴离子变化率大的差异都是新的Ru Lewis酸[CpRu((S,S)- biphop-F)] +(biphop-F =(C 6 F 5)2 POCH 2(Ph)CH 2(Ph)OP(C 6 F 5)2)。配合物1的结构(L =甲基丙烯醛,Y = SbF 6)提供了路易斯酸和阴离子对亲二烯体的协同结合的证据。