Enyne-2-pyrone [4 + 4]-Photocycloaddition: Sesquiterpene Synthesis and a Low-Temperature Cope Rearrangement
摘要:
Intramolecular [4 + 4] photoreaction of 2-pyrones with a 1,3-enyne yields an unstable 1,2,5-cyclooctatriene product. Without a C4 pyrone substituent, 1,3-hydrogen migration converts the allene to a 1,3-diene, with a skeleton related to dactylol. With methoxy substitution, Cope rearrangement yields a nine-membered ring fused to a cyclobutane. Both structures were confirmed by X-ray crystallography. The Cope rearrangement is apparently reversible, reforming the allene which undergoes a proton shift to the more stable 1,3-diene product.
Lithium Hydroxide Assisted
<i>Endo</i>
‐Selective [4+4]‐Photocycloaddition of Pyran‐2‐ones
作者:Lei Li、William L. Turnbull、Robert McDonald、F. G. West
DOI:10.1002/ejoc.202100122
日期:2021.4.26
Readily accessible 3‐acyl‐4‐hydroxypyran‐2‐ones with pendent furans undergo [4+4]‐photocycloaddition reactions in the presence of lithium ion to afford lactone‐bridged cyclooctenones with complete selectivity for the endo cycloadducts.
Cyclooctatrienes from pyran-2-ones via a tandem [4 + 4]-photocycloaddition/decarboxylation process
作者:Lei Li、Charles E. Chase、F. G. West
DOI:10.1039/b806871b
日期:——
Irradiation of pyran-2-ones bearing pendent furans in aqueous MeOH followed by heating furnished fused bicyclic products containing a cyclooctatriene ring.
Catalytic and Base‐free Suzuki‐type α‐Arylation of Cyclic 1,3‐Dicarbonyls via a Cyclic Iodonium Ylide Strategy
作者:Mingxuan Liang、Mengling He、Zhiqing Zhong、Bei Wan、Qingfeng Du、Shaoyu Mai
DOI:10.1002/anie.202400741
日期:2024.4.22
A general and catalytic α-arylation of cyclic 1,3-dicarbonyls have been developed, providing expedient access toward a wide range of high-value 2-aryl (hetero)cyclic 1,3-dicarbonyls. The key to success is through a cyclic iodonium ylide strategy. Our approach is base-free and exhibits broad substrate scope (>100 examples). Importantly, our approach allows late-stage modification and significantly simplifying