<i>anti</i>-Diastereo- and Enantioselective Carbonyl Crotylation from the Alcohol or Aldehyde Oxidation Level Employing a Cyclometallated Iridium Catalyst: α-Methyl Allyl Acetate as a Surrogate to Preformed Crotylmetal Reagents
作者:In Su Kim、Soo Bong Han、Michael J. Krische
DOI:10.1021/ja808857w
日期:2009.2.25
catalyst generated in situ from [Ir(cod)Cl](2), 4-cyano-3-nitrobenzoic acid and the chiral phosphine ligand (S)-SEGPHOS, alpha-methyl allyl acetate couples to alcohols 1a-1j with complete levels of branched regioselectivity to furnish products of carbonyl crotylation 3a-3j, which are formed with good levels of anti-diastereoselectivity and exceptional levels of enantioselectivity. An identical set of optically
在使用由[Ir(cod)Cl](2)、4-氰基-3-硝基苯甲酸和手性膦配体(S)-SEGPHOS原位生成的邻位环金属化铱催化剂进行转移氢化的条件下,α-甲基乙酸烯丙酯与具有完全支化区域选择性水平的醇1a-1j偶联,提供羰基巴豆酰化产物3a-3j,形成的产物具有良好水平的反非对映选择性和异常水平的对映选择性。在相同的条件下,但使用异丙醇作为末端还原剂,可以从相应的醛2a-2j得到一组相同的光学富集的羰基巴豆酰化产物3a-3j。旨在探索立体选择起源的实验建立了 (R)-乙酸酯和经 (S)-SEGPHOS 修饰的铱催化剂的匹配电离模式,以及烯丙基乙酸酯的可逆电离和快速 pi 面相互转化。在CC键形成之前产生吡啶基中间体。此外,还证明了在羰基加成之前的快速醇-醛氧化还原平衡。因此,在不存在任何化学计量金属试剂或化学计量金属副产物的情况下,实现了醇或醛氧化水平的反非对映选择性和对映选择性羰基巴豆酰化。
Toward Creation of a Universal NMR Database for Stereochemical Assignment: Complete Structure of the Desertomycin/Oasomycin Class of Natural Products
作者:Yoshihisa Kobayashi、Choon-Hong Tan、Yoshito Kishi
DOI:10.1021/ja004154q
日期:2001.3.1
A stereocontrolled synthetic route to the C1C18 subunit of pamamycin-607
作者:Sung Ho Kang、Joon Won Jeong
DOI:10.1016/s0040-4039(02)00655-x
日期:2002.5
The C1 C18 subunit 2 of the 16-membered macrodiolide pamamycin-607 has been synthesized stereo selectively using the Ag2CO3-mediated intramolecular iodoetherification for the two cis-2,5-disubstituted tetrahydrofurans, crotylation and cuprate epoxide opening for the hydroxyl and methyl substituents. (C) 2002 Elsevier Science Ltd. All rights reserved.
Enantioselective Total Synthesis of Bistramide A
作者:Michael T. Crimmins、Amy C. DeBaillie
DOI:10.1021/ja057686l
日期:2006.4.1
The enantioselective synthesis of bistramide A has been achieved with a longest linear sequence of 18 steps. The synthetic strategy involves the use of a distereoselective glycolate alkylation, an aldol addition of a chlorotitanium enolate of N-acylthiazolidinthione, and a Sharpless asymmetric epoxidation to synthesize the three key fragments.
Bistramide A 的对映选择性合成已通过最长的 18 步线性序列实现。合成策略包括使用非对映选择性乙醇酸烷基化、N-酰基噻唑烷硫酮的氯钛烯醇化物的羟醛加成和 Sharpless 不对称环氧化来合成三个关键片段。
Toward Creation of a Universal NMR Database for the Stereochemical Assignment of Acyclic Compounds: Proof of Concept
作者:Jinhwa Lee、Yoshihisa Kobayashi、Kenichi Tezuka、Yoshito Kishi
DOI:10.1021/ol990379y
日期:1999.12.1
[formula: see text] Using the C.5-C.10 portion of the oasomycinclass of naturalproducts, the reliability and usefulness of an NMRdatabase for the stereochemicalassignment of acyclic compounds has been demonstrated. The predicted relative stereochemistry based on the NMRdatabase has unambiguously been established via synthesis.