Synthesis of <i>β</i>-Lactams from Isocyanates and Vinyl Ethers under High Pressure

Abstract

Abstract The [2 + 2]cycloaddition of phenyl isocyanate to 2,3-dihydrofuran was appreciably accelerated by compression to produce a β-lactam ring; its apparent activation volume was estimated to be −28 ml mol−1. Similar β-lactams were obtained under high pressure in the reaction of phenyl isocyanate with various vinyl ethers. Although the [2 + 2]cycloaddition of alkyl isocyanates to 2,3-dihydrofuran was also accelerated under high pressure to give β-lactams with good yields; the reactions of alkyl isocyanates with ethyl vinyl ether were slow, even at high pressure.