Facile synthesis and desulfurization of 5-(phenylthio)pyrano[3,2-c][1]benzopyrans starting from 5-phenylthio-4-penten-1-ols and salicylaldehyde via in situ intramolecular cycloaddition of substituted o-quinonemethides
摘要:
5-(Phenylthio)pyrano[3,2-c][1]benzopyrans (6) were successfully synthesized in high yield by the reaction of 5-phenylthio-4-penten-1-ol (5) and salicylardehyde (1) in benzene in the presence of p-toluenesulfonic acid and trimethyl orthoformate. trans,trans-Isomer 6a and cis,cis-isomer 6d were produced as major products from (E)-5 and (Z)-5, respectively. Treatment of 6a with lithium 4,4'-di-tert-butylbiphenyl or Raney Ni (W-4) lead to trans-pyrano[3,2-c][1]benzopyran 4b which is very difficult to make by direct cycloaddition using unsubstituted 4-penten-1-ol (2b). (C) 2000 Elsevier Science Ltd. All rights reserved.
Indirect Cation Pool Method. Rapid Generation of Alkoxycarbenium Ion Pools from Thioacetals
作者:Seiji Suga、Kouichi Matsumoto、Koji Ueoka、Jun-ichi Yoshida
DOI:10.1021/ja0625778
日期:2006.6.1
the electrochemical generation and accumulation of ArS(ArSSAr)+ at low temperature (step 1) and the follow-up reaction with a thioacetal to generate an alkoxycarbeniumion pool (step 2), which reacts with various carbonnucleophiles (step 3). Steps 2 and 3 are extremely fast. The electrogenerated ArS(ArSSAr)+ was well-characterized by 1H NMR and CSI-MS. The alkoxycarbeniumion pool generated by the
Anti-Markovnikov Addition of Thiols Across Double Bonds Catalyzed by H-Rho-Zeolite
作者:Pradeep Kumar、Rajesh Kumar Pandey、Vishnumurthy R. Hegde
DOI:10.1055/s-1999-2976
日期:1999.12
A variety of olefins react with thiols in the presence of a catalytic amount of H-Rho-zeolite to afford the corresponding anti-Markovnikov addition products in good to excellent yields.
Direct and indirect electrochemical generation of alkoxycarbenium ion pools from thioacetals
作者:Kouichi Matsumoto、Koji Ueoka、Shinkiti Suzuki、Seiji Suga、Jun-ichi Yoshida
DOI:10.1016/j.tet.2009.09.020
日期:2009.12
Thioacetals were found to be effective precursors to generate and accumulate alkoxycarbeniumions based on direct and indirect cation pool methods. Alkoxycarbeniumions thus generated reacted with carbonnucleophiles such as allylsilanes and enol silyl ethers to give C–C bond formation products in good yields.
Regioselective Hydrothiolation of Alkenes Bearing Heteroatoms with Thiols Catalyzed by Palladium Diacetate
作者:Taichi Tamai、Akiya Ogawa
DOI:10.1021/jo500586a
日期:2014.6.6
examples of transition-metal-catalyzed hydrothiolation of alkynes, the corresponding catalytic addition of thiols to alkenes has remained undeveloped. However, a novel Pd-catalyzed addition of thiols to alkenes bearing a heteroatom, such as oxygen and nitrogen, is found to proceed under mild conditions to give the corresponding Markovnikov adducts, regioselectively, in good yields.
Lithium Bromide, a Novel and Highly Effective Catalyst for Monothioacetalization of Acetals under Mild Reaction Conditions
作者:Fumiaki Ono、Ryojyu Negoro、Tsuneo Sato
DOI:10.1055/s-2001-17477
日期:——
Lithium bromide is efficient as a catalyst for the monothioacetalization of acetals under mild reaction conditions to provide products in excellent yields with high chemoselectivity.