Photoredox Generated Carbonyl Ylides Enable a Modular Approach to Aryltetralin, Dihydronaphthalene, and Arylnaphthalene Lignans
作者:Edwin Alfonzo、Alexandra M. Millimaci、Aaron B. Beeler
DOI:10.1021/acs.orglett.0c02286
日期:2020.8.21
A one-pot synthesis of dihydronaphthalenes and arylnaphthalenes from epoxides and common dipolarophiles is described. The reaction proceeds through photoredox activation of epoxides to carbonyl ylides, which undergo concerted [3 + 2] dipolar cycloaddition with dipolarophiles to provide tetrahydrofurans or 2,5-dihydrofurans. In the same flask, acid promoted rearrangement affords densely functionalized
The photochemistry of 2,3-bis(p-methoxyphenyl)oxirane: trapping of a C–C cleaved intermediate in an electron-transfer sensitised process
作者:Paul Clawson、Patricia M. Lunn、Donald A. Whiting
DOI:10.1039/c39840000134
日期:——
2,3-Bis(p-methoxyphenyl)oxirane (6) rearranges, with C–O cleavage, to the carbonyl compounds (8) and (9) on irradiation, direct or triplet sensitised, and thermally: in contrast C–C cleavage is observed with dicyanoanthracene as electron-transfersensitiser, and the resulting intermediate can be trapped by dipolarophiles in synthetically useful reactions.
A sterically encumbered photoredox catalyst enables the unified synthesis of the classical lignan family of natural products
作者:Edwin Alfonzo、Aaron B. Beeler
DOI:10.1039/c9sc02682g
日期:——
selectively generate carbonyl ylides from electron-rich epoxides. These can undergo concerted [3 + 2] dipolarcycloadditions to afford tetrahydrofurans, which were advanced (2–4 steps) to at least one representative natural product or natural product scaffold within all six subtypes in classical lignans. The application of those synthetic blueprints to the synthesis of heterolignans bearing unnatural