The Scope of Catalytic Enantioselective Tandem Carbonyl Ylide Formation−Intramolecular [3 + 2] Cycloadditions
摘要:
Catalytic enantioselective tandem carbonyl ylide formation-intramolecular 1,3-dipolar cycloaddition reactions of 2-diazo-3,6-diketoesters show promising scope in terms of asymmetric induction as the tethered alkene/alkyne dipolarophile component is varied. Cycloadditions were found to occur in moderate to very good yields, with a difference in ee exhibited by the electronically different 2-diazo-3,6-diketoesters 1, 25 and 33, 34. Values for ee of up to 90% for alkene dipolarophiles and up to 86% for alkyne dipolarophiles were obtained.
Zirconocene-Induced Cocyclisation/Elimination Reactions of 2-Heterosubstituted 1,6-Dienes and 1,6-Enynes
作者:Richard J. Whitby、David R. Owen
DOI:10.1055/s-2005-870029
日期:——
Zirconocene-mediated cocyclisation of 2-heterosubstituted-1,6-dienes and -enynes gave zirconacycles bearing an endocyclic β-leaving group which eliminated under the reaction conditions to provide exocyclic alkylidene groups. The scope of this cyclisation/elimination has been investigated along with further elaboration of the monosubstituted zirconocene intermediates by insertion of alkenyl carbenoids.
stereoselective construction of the trisubstituted double bonds in (10) which is a precursor to the oxepane ring system (12) of zoapatanol (1); subsequent elaboration of (12) gave (1R*,4S*,5R*)-4-[5-oxo-8-methylnon-7-enyl]-3,8-dioxabicyclo[3.2.1]octane-1-acetic acid (18), a demethyl analogue of the potent antigestational agent ORF 13811 (2).
一种Ni 0的MeMgBr与二氢呋喃( -催化的偶联4)并添加格氏试剂(的7),以一丁炔-1,4-二醇衍生物(8)是在三取代双键的高度立体选择性构建的关键步骤(10),其为唑烷醇(1)的氧杂环丁烷环系统(12)的前体;随后的(12)的加工得到(1R *,4 S *,5 R *)-4- [5-氧代-8-甲基非-7-烯基] -3,8-二氧杂双环[3.2.1]辛烷-1 -乙酸(18),是有效的抗妊娠剂ORF 13811(2)的脱甲基类似物。
A stereoselective synthesis of trisubstituted alkenes. Part 1. Nickel-catalysed coupling of Grignard reagents with 5-alkyl-2,3-dihydrofurans
作者:Philip J. Kocieński、Martin Pritchard、Sjoerd N. Wadman、Richard J. Whitby、Clive L. Yeates
DOI:10.1039/p19920003419
日期:——
5-Alkyl-2,3-dihydrofurans 3a–j prepared by the alkylation of 5-lithio-2,3-dihydrofuran 2 with primary alkyl bromides and iodides, undergo Ni0-catalysed coupling with Grignardreagents to give homoallylicalcohols. The yield and stereoselectivity depend on the structure of the Grignardreagent with the best results being obtained with long chain primary Grignardreagents and Grignardreagents lacking
通过5-lithio-2,3-二氢呋喃2与伯烷基溴化物和碘化物的烷基化反应制得的5-烷基-2,3-二氢呋喃3a – j与Niignyard试剂进行Ni 0催化偶联,得到均丙醇。产率和立体选择性取决于格氏试剂的结构,使用长链伯氏格氏试剂和缺少β-氢的格氏试剂(Me,Ph,Me 3 SiCH 2)可获得最佳结果。5-(1-羟基烷基)-2,3-二氢呋喃20和21是偶联反应的不良底物。提出了用于偶合以及竞争性还原和异构化反应的机理。
A Total Synthesis of (±)-Zoapatanol and Demethyl-ORF13811
作者:Philip J. Kocieński、Christopher J. Love、Whitby Richard J、Gerard Costello、David A. Roberts
DOI:10.1016/s0040-4020(01)89243-7
日期:1989.1
KOCIENSKI, PHILIP J.;LOVE, CHRISTOPHER J.;WHITBY, RICHARD J.;COSTELLO, GE+, TETRAHEDRON, 45,(1989) N2, C. 3839-3848
作者:KOCIENSKI, PHILIP J.、LOVE, CHRISTOPHER J.、WHITBY, RICHARD J.、COSTELLO, GE+