Preparation of arylpropiolate esters from trichlorocyclopropenium cation and elaboration of the esters to unsymmetrical 1,4-pentadiyn-3-ones and unsymmetrical tellurapyranones
铜(I)催化剂可通过使用合适的有机碱将二氧化碳插入炔烃的C H键中,利用该有机碱在热力学上可实现对羧酸盐的氢化以及碱的再生。在催化氯化铜(I)/ 4,7-二苯基-1,10-菲咯啉,聚合物结合的三苯基膦和2,2,6,6-四甲基哌啶为碱的情况下,末端炔烃在15 bar CO下进行羧化反应2,室温。过滤后,可以在铑/钼催化剂下将炔羧酸铵氢化为伯醇和水,以再生胺碱。这证明了无盐整体工艺的可行性,在该工艺中,二氧化碳可充当CH功能中C1的基石。
three-component coupling of acyl fluorides, silyl enol ethers, and alkynoates. The key to the success of the reaction is the formal transmetalation between pentacoordinate P(V) species (i.e., fluorophosphorane) and a silyl enol ether, which allows for C–C bond formation between the polarity-mismatched sites. The bond formation that cannot be attained even by transition metal catalysis is accomplished
Oligosubstituted Pyrroles Directly from Substituted Methyl Isocyanides and Acetylenes
作者:Alexander V. Lygin、Oleg V. Larionov、Vadim S. Korotkov、Armin de Meijere
DOI:10.1002/chem.200801395
日期:2009.1
methyl isocyanides 1 onto the triple bond of electron‐deficient acetylenes 2 represents a direct and convenient approach to oligosubstituted pyrroles 3. The scope and limitations of this reaction (24 examples, 25–97 % yield) are reported along with an optimization of the reaction conditions and a rationalization of the mechanism. In addition, a related newly developed CuI‐mediated synthesis of 2,3‐disubstituted
Organocatalytic
<i>trans</i>
Phosphinoboration of Internal Alkynes
作者:Russell G. Fritzemeier、Jan Nekvinda、Christopher M. Vogels、Carol Ann Rosenblum、Carla Slebodnick、Stephen A. Westcott、Webster L. Santos
DOI:10.1002/anie.202006096
日期:2020.8.17
We report the first trans phosphinoboration of internal alkynes. With an organophosphine catalyst, alkynoate esters and the phosphinoboronate Ph2P‐Bpin are efficiently converted into the corresponding trans‐α‐phosphino‐β‐boryl acrylate products in moderate to good yield with high regio‐ and Z‐selectivity. This reaction operates under mild conditions and demonstrates good atom economy, requiring only
Rhodium(III)-Catalyzed Redox-Neutral Cascade [3 + 2] Annulation of <i>N</i>-Phenoxyacetamides with Propiolates via C–H Functionalization/Isomerization/Lactonization
A Rh(III)-catalyzed cascade [3 + 2] annulation of N-phenoxyacetamides with propiolates under mild conditions using the internal oxidative O–N bond as the directing group has been achieved. This catalytic system provides a regio- and stereoselective access to benzofuran-2(3H)-ones bearing exocyclic enamino motifs with exclusive Z configuration selectivity, acceptable to good yields and good functional
Catalytic Dearomatization Approach to Quinolizidine Alkaloids: Five Step Total Synthesis of (±)-Lasubine II
作者:Michael J. James、Niall D. Grant、Peter O’Brien、Richard J. K. Taylor、William P. Unsworth
DOI:10.1021/acs.orglett.6b03017
日期:2016.12.16
operationally simple and mild reaction conditions are a significant improvement over previously reported thermal cyclizations. The quinolizinone products were also used in a novel dearomatization strategy to prepare 0.53 g of the alkaloid lasubine II in five steps and 36% overall yield.