2-oxo-3-butenoate esters as dienophiles and their utility in a novel synthesis of pyrroles
摘要:
Trisubstituted pyrroles of type 8 have been prepared in a regiospecific fashion by a two step sequence involving Diels-Alder reaction of 2-oxo-3-butenoate esters 1 with 2-alkoxy-1,3-pentiadiene derivatives 13, followed by ozonolysis and Paal-Knorr cyclization.
Rhodium‐Catalyzed Enantioselective [4+2] Cycloadditions of Vinylcarbenes with Dienes
作者:Bowen Zhang、Huw M. L. Davies
DOI:10.1002/anie.201914354
日期:2020.3.16
The reaction of 2-siloxycyclo-1,3-dienes with E-vinyldiazoacetates in the presence of the bulky chiral dirhodium tetracarboxylate catalyst, Rh2 (R-p-PhTPCP)4 results in an enantioselective [4+2] cycloaddition, in which three new stereogenic centers are formed. The [4+2] cycloadducts are generated as single diastereomers with high enantiocontrol (95-98 % ee). When the diene contains an additional stereogenic
Asymmetric Diels-Alder reactions of chiral N-methacryloylsultams with 1,3-dienes
作者:Wolfgang Oppolzer、Boris M. Seletsky、Gérald Bernardinelli
DOI:10.1016/s0040-4039(00)73222-9
日期:1994.5
undergoes efficient, endo-selective and highly diastereoface controlled [4+2]-additions to cyclopentadiene, isoprene, (E)-piperylene and the 2-silyloxydienes 10 and 12. The resulting crystalline cycloadducts are smoothly reduced with LiAlH4 providing the recovered auxiliary and the corresponding enantiomericallypure alcohols.
R 2 AlCl配位的N-甲基丙烯酰胺基1c经过高效,内选择性和高度非对映体控制的[4 + 2]加成到环戊二烯,异戊二烯,(E)-亚戊二烯和2-甲硅烷基氧二烯10和12上。用LiAlH 4平滑地还原所得的结晶环加合物,提供了回收的助剂和相应的对映体纯的醇。
Design of Chiral <i>N</i>-Triflyl Phosphoramide as a Strong Chiral Brønsted Acid and Its Application to Asymmetric Diels−Alder Reaction
作者:Daisuke Nakashima、Hisashi Yamamoto
DOI:10.1021/ja062508t
日期:2006.8.1
A highly reactive and acidic chiral Brønsted acid catalyst, chiral N-triflyl phosphoramide, was developed. Highly enantioselective Diels-Alderreaction of alpha,beta-unsaturated ketone with silyloxydiene was demonstrated using this chiral Brønsted acid catalyst.
Reversal of the Regiochemistry in the Rhodium-Catalyzed [4+3] Cycloaddition between Vinyldiazoacetates and Dienes
作者:Pablo E. Guzmán、Yajing Lian、Huw M. L. Davies
DOI:10.1002/anie.201406440
日期:2014.11.24
regio‐, diastereo‐, and enantioselective [4+3] cycloadditionbetween vinylcarbenes and dienes has been achieved using the dirhodium tetracarboxylate catalyst [Rh2(S‐BTPCP)4]. This methodology provides facile access to 1,4‐cycloheptadienes that are regioisomers of those formed from the tandem cyclopropanation/Cope rearrangement reaction of vinylcarbenes with dienes.
Asymmetric Diels–Alder Reactions with Chiral Acetylenic Carbene Complexes as Dienophiles
作者:Annette Rahm、Arnold L. Rheingold、William D. Wulff
DOI:10.1016/s0040-4020(00)00209-x
日期:2000.7
A new synthetic method is developed for the asymmetric Diels–Alder reactions of acetylenic dienophiles. Acetylenic Fischer carbene complexes with chiral pyrrolidines as the heteroatom stabilizing substituent were anticipated to block three of the four possible approaches of a diene and lead to selective asymmetric cycloadditions. A series of complexes of the type (CO)5MC((C4H7N)CR2OMe)CCH (M=Cr,
开发了一种新的合成方法用于炔属双亲亲烯的不对称Diels-Alder反应。预计具有手性吡咯烷作为杂原子稳定取代基的乙炔费休卡宾卡宾配合物会阻止二烯的四种可能途径中的三种,并导致选择性不对称环加成反应。一系列的类型(CO)的配合物的5 MC((C 4 H ^ 7 N)CR 2OMe)C haveCH(M = Cr,W; R = H,Me,Ph)是通过氨解相应的甲氧基配合物而制备的,该配合物的末端乙炔被保护为硅烷。如果炔烃被保护为三异丙基甲硅烷基,则迈克尔的加成被完全抑制,并且在通过吡咯烷的1,2-加成进行氨解后,末端炔基卡宾配合物可以在原去甲硅烷基化反应中主要作为E-异构体获得。这些配合物的E-异构体(而不是Z-异构体)的环加成反应是通过2-三异丙基甲硅烷氧基-1,3-戊二烯(66-73%de)的显着不对称诱导而发生的,而与环戊二烯和α-三异丙基甲硅烷氧基乙烯基环己烯则没有。提出了一个模型来说明观察到的立体选择性。