Regioselectivity Influences in Platinum-Catalyzed Intramolecular Alkyne O–H and N–H Additions
作者:Jeff P. Costello、Eric M. Ferreira
DOI:10.1021/acs.orglett.9b03557
日期:2019.12.20
The steric and electronic drivers of regioselectivity in platinum-catalyzed intramolecular hydroalkoxylation are elucidated. A branch point is found that divides the process between 5-exo and 6-endo selective processes, and enol ethers can be accessed in good yields for both oxygen heterocycles. The main influence arises from an electronic effect, where the alkyne substituent induces a polarization
A facile synthesis of aryldihydropyrans using a Sonogashira–selenoetherification strategy
作者:Margaret A Brimble、Gabrielle S Pavia、Ralph J Stevenson
DOI:10.1016/s0040-4039(02)00065-5
日期:2002.2
with a range of phenyl and naphthyl bromides affords the appropriate aryl acetylenic alcohols which then undergo ready reduction to the corresponding (E)-1-aryl-5-hydroxyalkenes. Subsequent selenoetherification of the (E)-5-hydroxyalkenes proceeds via a 6-endo-trig pathway cleanly affording the trans-2-aryl-3-phenylselenyltetrahydropyrans. Finally oxidativeelimination of the selenides afforded the 2-aryl-2
Tetrahydroxydiboron-Promoted Radical Addition of Alkynols
作者:Ze-Ying Sun、Sen Zhou、Kai Yang、Minjie Guo、Wentao Zhao、Xiangyang Tang、Guangwei Wang
DOI:10.1021/acs.orglett.0c02367
日期:2020.8.7
Tetrahydroxydiboron has previously been used as a borylation or reducing reagent in organic synthesis. Herein, we present a novel tetrahydroxydiboron-promoted radicaladdition of internal alkynes followed by intramolecular oxidation of alcohol through 1,5-hydrogen atom transfer. Preliminary mechanistic studies showed that the process might be initiated through N,N-dimethylformamide-assisted homolytic
Regioselective electrochemical radical cascade cyclization of internal alkynes to selenated and trifluoromethylated dihydropyran
作者:Mingming Yu、Tiantian Huang、Lin Zhang、Muhammad Shabbir、Yuhan Gao、Yi-Hung Chen、Hong Yi、Aiwen Lei
DOI:10.1007/s11426-023-1703-8
日期:2023.11
trifluoromethylated DHP compounds. The reaction proceeded smoothly under mild electrolysis conditions. The broad substrate scope (>50 examples) and scalablesynthesis demonstrated the complexity-building potential of the strategy. Initial mechanistic studies reveal that cyclization may involve a radical process. This protocol may promote the further development of diversified synthesis of multi-substituted dihydropyran
remote functionalizations based on alkene isomerization. In contrast, protocols based on alkyne isomerization are comparatively rare. Herein, we report a general Pd-catalyzed long-range isomerization of alkynyl alcohols. Starting from aryl-, heteroaryl-, or alkyl-substituted precursors, the optimized system provides access preferentially to the thermodynamically more stable α,β-unsaturated aldehydes