Palladium(O)-catalyzed alkylation of various allylic carbonates by aromatic thiols allowed the easy preparation of various allylic aryl sulphides in quite good yields. The reaction was regioselective with substitution at the less hindered side of the π-allyl system whatever the temperature of the reaction, and was diastereoselective with net retention of configuration.
The reaction of 1,4-bis(methoxycarbonyloxy)but-2-ene (2a–3a) or 3,4-bis(methoxycarbonyloxy)but-1-ene (4a) with various substituted benzene-1,2-diols was catalyzed by a palladium(0) complex to give substituted 2-vinyl-2,3-dihydro-benzo[1,4]dioxins in good yields via a tandem allylic substitutionreaction. In the case of 4-substituted benzene-1,2-diols, the ratio of regioisomers is determined by the
1,4-双(甲氧基羰基氧基)丁-2-烯(2a-3a)或3,4-双(甲氧基羰基氧基)丁-1-烯(4a)与各种取代苯-1,2-二醇的反应被催化通过钯(0)配合物通过串联烯丙基取代反应以良好的产率得到取代的2-乙烯基-2,3-二氢-苯并[1,4]二恶英。在 4-取代苯-1,2-二醇的情况下,区域异构体的比例由两个酚质子的相对酸度决定。对于 3-取代的苯-1,2-二醇,在烷基取代基的情况下,该比率仅由空间效应决定,尽管它主要由其他取代基的相应酚盐的相对稳定性决定;然而,对于 3-nitrobenzo-1,2-diol,这个比例是由 2-nitro- or 3-nitrophenate 的相对离去基团能力决定的。
Synthesis of allyl aryl sulphides by palladium(0)-mediated alkylation of thiols
作者:Catherine Goux、Paul Lhoste、Denis Sinou
DOI:10.1016/s0040-4039(00)74729-0
日期:1992.12
Various allylic aryl sulphides are readily prepared in high yields by the palladium(0)-catalyzed S-alkylation of allylic carbonates by various aromatic thiols.
New Process for the Preparation of Methyl Carbonates
作者:Peter G. M. Wuts、Scott W. Ashford、Andrew M. Anderson、Joseph R. Atkins
DOI:10.1021/ol034274d
日期:2003.5.1
graphicThe methyl carbonate of HOBt was developed for the conversion of alcohols to carbonates. This method is superior to the use of methyl chloroformate or methyl pyrocarbonate, especially with more hindered alcohols. The reagent is a stable solid that is easily prepared on a multigram scale.
Goux Catherine, Lhoste Paul, Sinou Denis, Tetrahedron, 50 (1994) N 34, S 10321-10330