110512-33-9

Upstream product

• 67980-06-7 α-(2-methyl-1,3-oxathiolan-2-yl)acetanilide 
• 5234-68-4 5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide 

Downstream Products

• 42825-78-5 2-(chloromethyl)-5,6-dihydro-N-phenyl-1,4-oxathiin-3-carboxamide 
• 64754-74-1 2-methyl-1,3-oxathiolane-N-phenyl-2-ketocarboxamide 

Relevant academic research and scientific papers

Formation of bicyclic β-lactams from dichloro-1,4-oxathiane-3- carboxanilides: Nucleophilic substitution of nitrogen on anomeric carbon

Transformation of dichloro-1,4-oxathiane anilides (2) to bicyclic β- lactam (5) is described. In the presence of sodium hydride, an intramolecular nucleophilic substitution of nitrogen to anomeric carbon of 2 gave (1R*, 6R*)-1-chloro-6-methyl-7-phenyl-5-oxa-2-thia-7-azabicyclo[4,2,0]octan-8-ones (5). The reason for facile displacement at C-2 is attributable to neighboring group participation of sulfur and C-2 is anomeric. Plausible mechanisms for the formation of 2-chloromethyl-5,6-dihydro-N-phenyl-1,4-oxathiin-3- carboxyamide (4) under the neutral conditions, or 2,3-dihydroxy-2-methyl-N- phenyl-1,4-oxathiane-3, carboxyamide (9) in aqueous solution, or bicyclic β- lactam (5) in the presence of sodium hydride were proposed.

CONVERSION OF DIHYDRO-1,4-OXATHIIN-3-CARBOXAMIDE TO THE ISOMERIC DIHYDRO-1,4-OXATHIIN-2-CARBOXAMIDE

The preparation of isomeric dihydro-1,4-oxathiin (3) from the dihydro-1,4-oxathin (1) via dichloro-1,4-oxathiane (4) is described.Chlorination of 1 followed by treatment of the resulting dichloride (4) with aqueous acetone gave dihydroxy-1,4-oxathiin (5).The solvolysis to produce intermediate chlorohydrin (11) was favored relative to elimination reaction to give exomethylene compound (8).Dehydration of 5 followed by reduction afforded α-hydroxy-1,3-oxathiolane (2) which is a key compound to prepare the isomeric dihydro-1,4-oxathiin (3).The reason for more facile displacement of chlorine at C-2 in comparison with that at C-4 in 4 was also discussed.

Synthesis of Dihydro-1,4-oxathiins by Action of Chlorine on 1,3-Oxathiolanes

A new convenient synthesis of 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxylic acid derivatives 1 has been achieved by using the action of chlorine on 2-methyl-N-phenyl-1,3-oxathiolane-2-acetamide (4a) and 2-methyl-1,3-oxathiolane-2-acetic acid methyl ester (4b).From the initially formed chlorosulfonium salts 16 unobserved transient sulfenyl chlorides 5 were generated, followed by cyclization to probable oxonium ion 18 to produce dihydrooxathiins 1.In the chlorinolysis reactions of 4a and 4b minor byproducts were formed: respectively 2,3-dichloro-2-methyl-1,4-oxathiin-3-carboxanilide 12a and its methyl ester analogue 12b.While 12b was stable, 12a was unstable, transforming to the corresponding 2-chloromethyl compound 13.The mechanism of formation of 13 as well as relative stability of dichlorides 12a, 12b, and related compounds is also discussed.