82865-31-4

Upstream product

• 67-56-1 methanol 
• 82865-29-0 (Z)-4-benzylidene-2-phenylthiazol-5(4H)-one 
• 17606-70-1 (4Z)-4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-one 
• 186581-53-3 diazomethane 
• 82865-30-3 2,5-diphenyl-2-thiazoline-4-carboxylic acid 

Relevant academic research and scientific papers

Reactivity of (Z)-4-Aryliden-5(4 H)-thiazolones: [2 + 2]-Photocycloaddition, Ring-Opening Reactions, and Influence of the Lewis Acid BF3

The irradiation of (Z)-2-phenyl-4-aryliden-5(4H)-thiazolones 2 with blue light (465 nm) in CH2Cl2 solution promotes [2 + 2]-photocycloaddition of the exocyclic C═C bonds and the formation of the dispirocyclobutanes 3. This reaction takes place with high stereoselectivity, given that the ?-isomer (1,3 head-to-tail syn coupling) is formed in more than 90% yield in most of the cases. However, irradiation of 5(4H)-thiazolones 2 with blue light (456 nm) in dry MeOH in the presence of BF3·OEt2 leads to the monospirocyclobutanes 4 with full stereoselectivity, also affording the ?-isomer. A ring-opening reaction of only one of the thiazolone rings appears to have taken place in 4 upon methanolysis, leading to the corresponding ester and thioamide groups. The treatment of free 4-aryliden-5(4H)-thiazolones 2 with a base in alcohol (NaOR/ROH) also produces a ring-opening reaction of the heterocycle by methanolysis, although, under these reaction conditions, further intramolecular S-attack at the exocyclic C(H)═C bond and cyclization is observed, forming the dihydrothiazoles 5 or 6 as mixtures of cis (RS/SR)- and trans (RR/SS)-isomers with high diastereomeric excess. trans-(RR/SS)-Dihydrothiazoles 6 can be isolated as pure diastereoisomers by column chromatography. Surprisingly, dihydrothiazoles 5 can also be obtained by the treatment of 4-aryliden-5(4H)-thiazolones 2 with BF3·OEt2 in methanol in the absence of a base.

An Excursion into the Synthesis of Potential Angiotensin Converting Enzyme Inhibitors

An attempt to prepare dehydro analogues of 1 gave the expected tripeptide 2a, but rearrangement of a thiazolone derivative of ΔZ-Phe made only a thiazolinecarboxylic acid (8) available.The latter was also converted into a tripeptide (11) and both compounds, 2a and 11, showed moderate angiotensin converting enzyme inhibition.