Synthesis of 5,7-Diphenyl(-4-Alkyl)trihydro Pyrano |3,4-D||1,2,3|selenadiazoles and 5,7-Diphenyl(-1-Alkyl)trihydropyrano |3,4-D||1,2,3|thiadiazoles

Abstract

The title compounds were prepared by the oxidative cveli/ntion of scmicarbazonotctrahydropvran with selenium dioxide and thionyl chloride.

Reactivity of ketene dithiolates toward alkyl bromides

“…The reaction mixture was stirred for 8 h at room temperature and extracted with dichloromethane. The product obtained was identified as 5-oxo-2-(2,4,6-trioxopyrimidin-5-ylidene)- [1,3]dithiane-4-carboxylic acid ethyl ester (3) (Scheme 1). It seems that the initially formed [ethoxycarbonylmethylsulfanyl-(2,4,6-trioxopyrimidin-5-ylidene) methyl-sulfanyl]acetic acid ethyl ester undergoes Dieckmann cyclization resulting in the formation of 3.…”

“…Similarly, the reaction of thiobarbituric acid (2) with carbon disulfide in the presence of sodium hydride followed by alkylation with ethyl bromoacetate produced 5-oxo-2-(4,6-dioxo-2-thioxopyrimidin-5-ylidene)- [1,3]dithiane-4-carboxylic acid ethyl ester (4). On the other hand, the reaction of barbituric acid/thiobarbituric acid 1/2 with carbon disulfide in the presence of sodium hydride followed by treatment with phenacyl bromide resulted in 5-[bis-(2-oxo-2-aryl-ethylsulfanyl)methylene]pyrimidine-2,4,6-trione (5)/5-[bis-(2-oxo-2-arylethylsulfanyl)methylene]-2-thioxopyrimidine-4,6-dione (6).…”

“…5-Oxo-2-(2,4,6-trioxopyrimidin-5-ylidene)- [1,3]dithiane-4-carboxylic acid ethyl ester (3)/5-oxo-2-(4,6-dioxo-2-thioxopyrimidin-5-ylidene)- [1,3]dithiane-4-carboxylic acid ethyl ester (4): general procedure. To a solution of barbituric acid/ thiobarbituric acid (1, 1.28 g/2, 1.44 g, 10 mmol) dissolved in DMSO (15 mL), sodium hydride (0.46 g, 20 mmol) was added slowly while stirring at room temperature.…”

“…We have also studied the reaction of vinyl chloride with aroyl and arylsulfonyl chlorides under Friedel-crafts conditions which afforded unsaturated oxosulfones and bissulfones [2]. This methodology has been extended to prepare bis unsaturated oxosulfones and bissulfones [3]. These activated mono and bis unsaturated olefins have been used to develop different heterocyclic systems [4].…”

A Novel Route for the Synthesis of Unsaturated Oxo Sulfones and Bissulfones

“…When vinyl chloride gas was passed into the solution of acetyl chloride in chloroform in the presence of anhydrous aluminium chloride, instead of 1-acetyl-2-chloroethene, a trimerized product, 1,3,5-triacetylbenzene was obtained. 9 But under similar conditions, when vinyl chloride gas ( 2 ) was passed into the solution of aroyl chloride 1 , the expected 1-aroyl-2-chloroethene 3 10 was formed. The latter, on condensation with arylsodium sulfinates 4 in aqueous alcohol, resulted in 1-aroyl-2-arylsulfonylethenes 5 .…”