Chemoselectivity Switching in the Rhodium-Catalyzed Reactions of 4-Substituted-1-sulfonyl-1,2,3-triazoles with Allenols: Noticeable Differences between 4-Acyl- and 4-Aryl-Triazoles
作者:Benito Alcaide、Pedro Almendros、Israel Fernández、Teresa Martínez del Campo、Guillermo Palop、Mireia Toledano-Pinedo、Patricia Delgado-Martínez
DOI:10.1002/adsc.201801424
日期:2019.3.5
Tunable chemoselectivity (O‐ versus C‐attack) in the rhodium‐catalyzed reactions of allenols with 4‐substituted‐1‐sulfonyl‐1,2,3‐triazoles has been achieved through the replacement of the 4‐aryl substituent by a 4‐acetyl moiety.
Allenols versus Allenones: Rhodium-Catalyzed Regiodivergent and Tunable Allene Reactivity with Triazoles
作者:Benito Alcaide、Pedro Almendros、Sara Cembellín、Teresa Martínez del Campo、Guillermo Palop
DOI:10.1002/chem.201702468
日期:2017.10.4
2‐Pyrrolines and 6‐oxo‐hexa‐2,4‐dienals have been prepared through the divergent reactions of 1‐benzenesulfonyl‐4‐aryl‐1,2,3‐triazoles with functionalized allenes. The rhodium‐catalyzed reactions between allenols and 1‐benzenesulfonyl‐4‐aryl‐1,2,3‐triazoles yielded 2‐pyrrolines. This transformation is compatible with the presence of aliphatic, aromatic, heterocyclic, amide, and halogen functional groups
The synergy between metal catalysis and radical chemistry allows to surpass previous limitations of the reactions between allenols and sulfonylating reagents. Considering that previous studies of the reactivity of the allenol moiety with sulfonylating reagents have been limited to addition and rearrangement reactions lacking cyclization, we decided to modify the protocol for achieving a catalytic
Pd–Cu bimetallic catalyzed or Cu‐promoted preparation of attached‐ring bis(heterocyclic) fused cyclobutenes in a totally controlled fashion by using alkynehomocoupling, as well as a double [2+2] cyclization of the resulting bis(allenyne) in a domino sequence has been accomplished (see scheme).
The metal-free cyclization of allenylketones and p-toluenesulfonylmethyl isocyanide (TosMIC), promoted by Cs2CO3, provides a convenient access to tetrasubstituted pyrroles in which an acyl group undergoes 1,2-migration. This tandem Michael addition/annulative migration synthetic strategy is general and high-yielding for various substituted allenylketones. Moreover, a phosphoryl or ester moiety is
由 Cs 2 CO 3促进的联烯基酮和对甲苯磺酰甲基异氰化物 (TosMIC)的无金属环化提供了获得四取代吡咯的便捷途径,其中酰基经历 1,2-迁移。这种串联迈克尔加成/环状迁移合成策略对各种取代的丙二烯酮具有通用性和高产率。此外,磷酰基或酯部分也是使这种迁移成为可能的合适功能。