to excellent yields with high levels of stereoselectivity. Useful C3-unit elongation, which makes the best use of an allylether as a protecting group and a nucleophilic allylation agent, is demonstrated. Mechanisms for the umpolung reaction (of an allylether into an allylic anion) and stereoselectivity associated with allylation of aldehydes are discussed.
A new method for deprotecting tetrahydropyranyl and silyl ethers has been established by using organotin phosphate condensates as a catalyst. The reaction proceeds selectively under mild conditions. The heterogenous reaction enables easy separation of the catalyst, which can be reused for further reactions without purification.
Activation and synthetic applications of thiostannanes. Deprotection and transformations of tetrahydropyranyl ethers
作者:Tsuneo Sato、Junzo Otera、Hitosi Nozaki
DOI:10.1021/jo00302a057
日期:1990.7
Pd-Catalyzed Nucleophilic Alkylation of Aliphatic Aldehydes with Allyl Alcohols: Allyl, 2-Tetrahydrofuryl, and 2-Tetrahydropyranyl Ethers as Useful C3, C4, and C5 Sources
Efficient and Ecofriendly Protocol for Tetrahydropyranylation/Depyranylation of Alcohols in the Presence of Tin(II) Chloride Dihydrate
作者:Dipankoj Gogoi、Nabajyoti Baruah、Ghanashyam Bez
DOI:10.1080/00397910601055123
日期:2007.3
Abstract A mild, efficient, and solvent‐free protocol for tetrahydropyranylation of alcohols in the presence of a catalytic amount of SnCl2 · 2H2O is reported. Simple filtration of the reaction mixture through a short silica‐gel pad gives the pure products in excellent yields. Depyranylation can also be achieved by adding methanol under similar reaction conditions.