An Enantioselective Total Synthesis of (+)-Duocarmycin SA
作者:Michael A. Schmidt、Eric M. Simmons、Carolyn S. Wei、Hyunsoo Park、Martin D. Eastgate
DOI:10.1021/acs.joc.8b00285
日期:2018.4.6
An efficient, concise enantioselective total synthesis of the potent antitumor antibiotic (+)-duocarmycin SA is described. The invented route is based on a disconnection strategy that was devised to facilitate rapid and efficientsynthesis of key core compounds to enable preclinical structure–activity relationship investigations. The key tricycle core was constructed with a highly enantioselective
[figure: see text] This report describes a concise enantioselectivesynthesis of the A-ring synthon for the synthesis of 1 alpha-hydroxyvitamin D3 compounds. The synthesis involves two notable transformations: (I) stereoselective construction of the enol triflate from the vinyl ketone by Michael addition of Ph2P(O)Li followed by in situ triflation of the resulting enolate and (II) palladium-catalyzed
Synthesis, Coordination Behavior, and Structural Features of Chiral Amino-, Pyrazolyl-, and Phosphino-Substituted Ferrocenyloxazolines and Their Application in Asymmetric Hydrogenations
flexible and modular synthesis of 15 chiral nonracemic ferrocenyloxazolines—all based on a ferrocenylethyl backbone—is described. Starting from N,N-dimethylaminoethyl ferrocene a range of oxazolinederivatives with various oxazoline substituents were prepared in a three-step sequence. After reaction with methyl iodide, the quaternized dimethylamino group was replaced by different amino, pyrazolyl, and phosphinyl
Synthesis of 1-Methyl-6,10-diphenylheptalene Derivatives
作者:Xudong Jin、Anthony Linden、Hans-Jürgen Hansen
DOI:10.1002/hlca.200900435
日期:2010.4
(diphenylphospino)lithium (=lithium diphenylphosphanide) in THF at 0° (Scheme 4). However, the purification of 4a/4b was very difficult since these bis‐phosphines decomposed on column chromatography on silica gel and were converted mostly by oxidation by air to bis(phosphineoxides) 5a and 5b. Both 5a and 5b were also obtained in pure form by reaction of 3a or 3b with (diphenylphosphinyl)lithium (=lithium oxidodiphenylphospanide)
在THF中用二异丁基氢化铝(DIBAH)还原庚烯二酯1得到了庚烯1,2-二甲醇2a和其双键移位(DBS)异构体2b的混合物(方案3)。两种产物都可以通过硅胶柱色谱法分离。随后在CH 2 Cl 2中用PCl 5对2a或2b进行氯化,得到了1,2-双(氯甲基)庚二烯3a及其DBS异构体3b的混合物。长时间色谱分离后,产物3a和3b以纯净形式获得。它们在低温下从己烷/ Et 2 O 7:1平稳结晶,其结构通过X射线晶体结构分析确定(图1和2)。在0°下用THF中过量的(二苯基膦基)锂(=二苯基膦酸锂)容易地通过二苯基膦基进行3a或3b的Cl取代基的亲核交换(方案4)。但是,4a / 4b的纯化非常困难,因为这些双膦在硅胶柱色谱上分解并且大部分被空气氧化转化为双(氧化膦)5a和4b。5b。两个图5a和图5b也以纯的形式获得通过的反应图3a或3b中与(二苯基膦基)锂(=锂oxidodiphenylp
Selective C–P(O) Bond Cleavage of Organophosphine Oxides by Sodium
作者:Jian-Qiu Zhang、Eiichi Ikawa、Hiroyoshi Fujino、Yuki Naganawa、Yumiko Nakajima、Li-Biao Han
DOI:10.1021/acs.joc.0c01642
日期:2020.11.6
Sodium exhibits better efficacy and selectivity than Li and K for converting Ph3P(O) to Ph2P(OM). The destiny of PhNa co-generated is disclosed. A series of alkyl halides R4X and aryl halides ArX all react with Ph2P(ONa) to produce the corresponding phosphine oxides in good to excellent yields.