Reactions of Silica Chloride (SiO<sub>2</sub>Cl)/DMSO, a Heterogeneous System for the Facile Regeneration of Carbonyl Compounds from Thioacetals and Ring-Expansion Annelation of Cyclic Thioacetals
Thioketals without enolizable hydrogens adjacent to a sulfur atom are converted easily to the corresponding ketones in high yields under similar reaction conditions. However, thioketals with enolizable methyl and methylene groups undergo ring-expansion reactions to afford 1,4-dithiepins and 1,4-dithiins in dry CH(2)Cl(2) at room temperature in good yields.
An efficient method has been found for the preparation of cyclic monodithioacetats of 1,3-dicarbonyl compounds usingborontrifluorideetherate as the acid catalyst. Asymmetric 1,3-diketones react regioselectively in most of the cases tried. A study of the 13C and 1H nmr characteristics of these compounds has been carried out.
已经发现使用三氟化硼醚化物作为酸催化剂来制备1,3-二羰基化合物的环状单二硫代乙酸酯的有效方法。在大多数尝试过的情况下,不对称的1,3-二酮会发生区域选择性反应。已经对这些化合物的13 C和1 H nmr特性进行了研究。
New Applications of 2,4,6-Trichloro-1,3,5-triazine (TT) in Synthesis: Highly Efficient and Chemoselective Deprotection and Ring-Enlargement of Dithioacetals and Oxathioacetals
作者:Babak Karimi、Hassan Hazarkhani
DOI:10.1055/s-2003-42459
日期:——
Efficient deprotection of a wide variety of 1,3-dithioacetals and 1,3-oxathiolanes to the corresponding carbonyl compounds at room temperature using a combination of 2,4,6-trichloro-1,3,5-triazine (TT) and dimethyl sulfoxide (DMSO) was investigated. In this way, 1,3-oxathioacetals and 1,3-dithioacetals of enolizable ketones were converted to the corresponding 1,4-oxathiepine and 1,4-dithiepine derivatives, respectively.