通过简便的方法以良好的选择性和高效率获得了三取代的4 H-喹啉嗪-4-酮。在炔烃底物控制的基础上,温和且经济高效的反应具有广泛的底物范围(20个实例,产率高达93%),并且也易于扩大规模。产品上的活动站点允许进一步修改。炔烃底物的控制策略可以进一步扩展,以实现更复杂的三取代的4 H -quinolizin-4-one骨架。
A novel cyclization reaction of pyridinium 1,4-zwitterionic thiolates and propiolic acidderivatives mediated by triethylamine is described, which allows the facile synthesis of indolizines under mild reaction conditions. The net transformation involves an acetylide-driven formal [5 + 1] annulation reaction followed by a spontaneous ring-contraction/sulfur extrusion process of transient pyridothiazine
Pyridinium 1,4‐zwitterionic thiolates as a class of sulfur‐containing synthons were applied to a [3+2] cascade cyclization reaction with activated alkynes, affording a library of polysubstitutedthiophenes with excellent regioselectivities, especially those bearing multifarious fluorine‐containing groups.
Regio‐ and Stereoselective Synthesis of 1,1‐Diborylalkenes via Brønsted Base‐Catalyzed Mixed Diboration of Alkynyl Esters and Amides with BpinBdan
作者:Xiaocui Liu、Wenbo Ming、Xiaoling Luo、Alexandra Friedrich、Jan Maier、Udo Radius、Webster L. Santos、Todd B. Marder
DOI:10.1002/ejoc.202000128
日期:2020.4.7
1‐diborylalkene products can be utilized in Suzuki–Miyaura cross‐coupling reactions which take place selectivly at the C–B site. DFT calculations suggest the NaOtBu‐catalyzed mixed 1,1‐diboration of alkynes occurs through deprotonation of the terminal alkyne, stepwise addition of BpinBdan to the terminal carbon followed by protonation with tBuOH. Experimentally observed selective formation of (Z)‐diborylalkenes
Stabilization of γ-lactam and lactone ring-fused norcaradienes by protonation: DFT calculations of norcaradiene and the corresponding cycloheptatriene structures
Abstract Stabilization of norcaradiene structures of γ-lactone and lactam ring-fused 7-vinylnorcaradienes 1a – 1e in their norcaradiene – cycloheptatriene valence isomerization was achieved by protonation. Induced 13 C NMR chemical shifts caused by protonation were monitored for the cyclopropane ring carbons (C1, C6 and C7) of the norcaradiene structures as indices of their stabilities. DFT calculations
摘要 γ-内酯和内酰胺环稠合的 7-乙烯基降卡二烯 1a - 1e 在其降卡二烯 - 环庚三烯价异构化中的降卡二烯结构的稳定是通过质子化实现的。监测由质子化引起的 13 C NMR 化学位移的降甲二烯结构的环丙烷环碳(C1、C6 和 C7)作为其稳定性的指标。降卡二烯、相应的环庚三烯及其质子化结构的 DFT 计算(B3LYP/6-311+G(d) 水平)支持实验结果。
Organosuperbase-Catalyzed 1,1-Diboration of Alkynes
作者:Son H. Doan、Nhan N. H. Ton、Binh Khanh Mai、Thanh Vinh Nguyen
DOI:10.1021/acscatal.2c03901
日期:2022.10.7
1,1-Diboryl alkenes are versatile building blocks in organic synthesis and medicinal chemistry. However, there have been only a small number of established methods to prepare this class of compounds, and most of them used transition-metal catalysts, which are undesirable in the preparation of biologically relevant compounds. Herein, we report an unprecedented application of P1–tBu phosphazene as a
1,1-二硼基烯烃是有机合成和药物化学中的通用组成部分。然而,目前只有少数成熟的方法来制备这类化合物,并且大多数使用过渡金属催化剂,这在生物相关化合物的制备中是不可取的。进来,我们报告一个前所未有的 P 1 – t应用Bu 磷腈作为超碱性有机催化剂促进未活化的芳香族和缺电子末端炔烃的 1,1-二硼化反应。这种磷腈的双 Brønsted 和 Lewis 碱度能够激活反应底物并获得高区域和立体选择性。彻底的实验和计算研究相结合,为这些磷腈催化的二硼化反应提出了有趣的机理见解,这些反应也得到了详细讨论。