Synthesis of Fused-β-Lactams through Selective Gold-Catalyzed Oxycyclization of Dioxolane-Tethered Enynes
摘要:
The gold-catalyzed preparation of 2-azetidinone-fused oxacycles was accomplished from beta-lactam-linked enynes through heterocyclization reaction taking advantage of the acetonide pendant group. While the synthesis of fused tetrahydrofuran-beta-lactams from 1,3-enynes could be considered as an unusual metal-catalyzed cyclization of enynols, alpha-alkoxy dioxolane-tethered 1,3-enynes exclusively undergo bis-oxycyclization to afford tricyclic bridged acetals.
Cu/Pd-catalyzed enantioselectivesynthesis of multisubstituted allenes is established. By employing chiral sulfoxide phosphine (SOP)/Cu and PdCl2 (dppf) complexes as catalysts, the 1,4-arylboration of 1,3-enynes provides an efficient approach to trisubstituted chiralallenes with up to 92 % yield and 97:3 er. Furthermore, by using 2-substituted 1,3-enynes as substrates, the tetrasubstitutedchiralallenes were
建立了铜/钯催化的多取代烯的对映选择性合成。通过使用手性亚砜膦(SOP)/ Cu和PdCl2(dppf)配合物作为催化剂,1,3-烯炔的1,4-芳基硼化提供了一种高效的三取代手性异戊烯的方法,收率高达92%和97:3 er 。此外,通过使用2-取代的1,3-烯炔作为底物,使用该策略成功地产生了四取代的手性烯丙基。最后,理论计算表明,烯丙基铜物种的金属转移是该转变的限速步骤。
Copper-Catalyzed Syntheses of Multiple Functionalizatized Allenes via Three-Component Reaction of Enynes
作者:Yulong Song、Chunling Fu、Shengming Ma
DOI:10.1021/acscatal.1c02140
日期:2021.8.6
oxime esters and 1,3-enynes in the presence of TMSCN or TMSCF3 has been developed. This mild protocol enjoys a broad substrate scope tolerating many functional groups, providing a facile access to 1,7-double-functionalized allenes, which are difficult to prepare. The allenyl nitrile products may be easily transformed into allenoic acid derivatives and stereodefined tetrasubstituted alkenes, demonstrating
method with high efficiency for the synthesis of α,β-unsaturated amides from the easily prepared propargyl alcohols and TMSN3 using TMSCl as an acid promoter is developed. A wide variety of α,β-unsaturated amides were produced in moderate to excellent yields. Mechanistic studies indicate that this transformation involves TMSCl-mediated allenylazide intermediate formation, C–C bond cleavage, and C–N
A novel and direct synthesis of 1‐aryl‐5‐arylvinyl‐tetrazoles from easily prepared propargylic alcohols and TMSN3 is developed in the presence of TMSCl under mild conditions (TMS=trimethylsilyl). The process involves an allenylazide intermediate, followed by a CC‐bond cleavage and CN‐bond formation to afford the desired products. Moreover, this method offers a good functional‐group applicability
Palladium-Catalyzed Oxidative Cross-Coupling of N-Tosylhydrazones or Diazoesters with Terminal Alkynes: A Route to Conjugated Enynes
作者:Lei Zhou、Fei Ye、Jiachen Ma、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201007224
日期:2011.4.4
Coming at them from another angle: In a fresh approach to the synthesis of conjugatedalkynes, the palladium‐catalyzed cross‐coupling of N‐tosylhydrazones or diazoesters with terminalalkynes provided the desired enyne products with excellent stereoselectivity (see scheme; Ts=p‐toluenesulfonyl). The reaction is proposed to involve an unprecedented alkynyl migratory insertion of a palladium carbene
从另一个角度出发:在一种新颖的共轭炔烃合成方法中,钯催化的N-甲苯磺酰hydr或重氮酸酯与末端炔烃的交叉偶联为所需的烯炔产物提供了出色的立体选择性(参见方案; Ts = p ‐甲苯磺酰基)。提出该反应涉及钯卡宾络合物的前所未有的炔基迁移插入。