Novel Syntheses of Enantiopure Hexahydroimidazo[1,5-b]isoquinolines and Tetrahydroimidazo[1,5-b]isoquinolin-1(5H)-ones via Iminium Cation Cyclizations
摘要:
Condensations of chiral diamines 11a-c with benzotriazole and formaldehyde gave benzotriazolyl intermediates 12a-c; similar condensations of alpha-amino-amides 10a-c with benzotriazole and paraformaldehyde gave 14a-c. Subsequent treatment of 12a-c and 14a-c with AlCl3 led to enantiopure tricyclic 1,2,3,5,10,10a-hexahydroimidazo[1,5-b]isoquinolines 1a-c and 2,3,10,10a-tetrahydroimidazo[1,5-b]isoquinolin-1(5H)-ones 15a-c, respectively, via Lewis acid promoted iminium cation cyclizations.
Chiral Primary−Tertiary Diamine Catalysts Derived From Natural Amino Acids for <i>syn</i>-Aldol Reactions of Hydroxy Ketones
作者:Jiuyuan Li、Sanzhong Luo、Jin-Pei Cheng
DOI:10.1021/jo802557p
日期:2009.2.20
A series of primary-tertiary diamine catalysts were designed and synthesized from primary natural amino acids. Application of these new chiral catalysts in direct aldol reactions of α-hydroxyketones showed very good catalytic activity (up to 97% yield) and high syn selectivity (up to syn/ anti = 30:1, 99% ee).
从伯天然氨基酸设计合成了一系列伯叔二胺催化剂。这些新的手性催化剂在α-羟基酮的直接醛醇缩合反应中的应用显示出非常好的催化活性(高达97%的收率)和高的合成选择性(高达syn / anti = 30:1,99%ee)。
Access to Spirocyclic Benzothiophenones with Multiple Stereocenters via an Organocatalytic Cascade Reaction
derivatives containing three stereocenters were prepared via one-step synthesis in yields ranging from 88 to 96% and in enantioselectivities (enantiomeric excess (ee)) ranging from 85 to 97%, with diastereoselectivities of approximately 14/2/1. Therefore, this method provides an efficientroute for the synthesis of a new class of opticallyactive 2-spirobenzothiophenones.
本报告描述了在金鸡纳生物碱胺存在下2-亚烷基苯并[ b ]噻吩酮衍生物与烯酮之间的有机催化级联反应。通过一步合成,制备了包含三个立体中心的螺苯并噻吩苯甲酸环己烷衍生物,其产率为88%至96%,对映选择性(对映体过量(ee))为85至97%,非对映选择性约为14/2/1。因此,该方法为合成新型的光学活性的2-螺苯并噻吩酮提供了有效的途径。
<scp>L</scp>-Phenylalanine Cyclohexylamide: A simple and convenient auxiliary for the synthesis of optically pure α,α-disubstituted (<i>R</i>)- and (<i>S</i>)-amino acids
synthesis of a series of optically pure α,α-disubstituted (R)- and (S)-amino acids of type 1, such as (R)- and (S)-2-methyl-phenylalanine (1a), (R)- and (S)-2-methyl-2-phenylglycine (1b), and (R)- and (S)-2-methylvaline (1c; Scheme 3). These amino acids were efficiently transformed into the suitably protected and activated amino acid building blocks (R)- and (S)-12b and (R)- and (S)-12c (Scheme 4) which are
Pd-Catalyzed Picolinamide-Directed C(sp2)–H Sulfonylation of Amino Acids/Peptides with Sodium Sulfinates
作者:Raghunath Bag、Nagendra K. Sharma
DOI:10.1021/acs.joc.4c00988
日期:2024.7.19
a Pd-catalyzed picolinamide-directed site-selective C(sp2)–H sulfonylation of amino acids and peptides with sodium sulfinates in moderate to good yields. Sulfonylation of levodopa and dopamine drug molecules and late-stage directed peptide sulfonylation are studied for the first time. Broad substrate scope having various functionalities, late-stage drug modifications, and various post synthetic utilities
Preparation of polymer-bound pyrazolone active esters for combinatorial chemistry
作者:Jang-Woong Byun、Dong-Hoon Lee、Yoon-Sik Lee
DOI:10.1016/j.tetlet.2003.09.044
日期:2003.10
The preparation of solid-phase active esters from a new pyrazolone linker resin is described. N-Acylation using this resin provides various amide products with a high conversion rate and good purity under mild conditions. The polymer-bound pyrazolone linkers are stable in the reaction conditions and are resistant to hydrolysis. Moreover, this resin can also be reused repeatedly without a loss of reactivity. (C) 2003 Published by Elsevier Ltd.