Four-component Asinger reaction

The four-component Asinger reaction between a-chloroisobutyraldehyde, ammonia, acetone, NaSH (X.=S) or water (X=0), was used to create 3-thiazoline and 3-oxazoline, which were used as building blocks for the realization of poly-oxa(thia)zolidine polymers 191 and 192 (14MCP412). 

The earliest reports of constrained Ugi adducts derived from bi-functional precursors appeared in the 1960s with the preparation of penicillin derivatives such as 68, involving sequential Asinger and Ugi four-component reactions (Scheme 11.13). As such, the synthesis represents the shortest preparation of a known penicillin derivative [65], The /Mactam ring is formed after isocyanide addition to the cyclic Schiff base, followed by carboxylate nitrilium ion trapping and acyl transfer to give the final penicillin core. In this example, the amine and carboxylic acid inputs may be considered tethered. 

A-3CR (A-4CR) Asinger three (four)-component reaction Ac acetyl... 

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