The extraordinary power of high‐pressure/solvent‐free conditions for the Diels–Alder reaction of thiophene has been established. For example, maleic anhydride (X=O) reacted with thiophene at 0.8 GPa and 100 °C to give the desired exo adduct in almost quantitative yield (see scheme). Further application of this method to maleimide (X=NR) and acrylic dienophiles demonstrated its remarkable potential.

For the first time, uncatalyzed, high‐pressure (0.6 GPa) reactions with ketones have proven to be a powerful way to perform the three‐component Strecker synthesis of α‐amino nitriles in high yields. Two types of double Strecker reactions were achieved, but attempts to perform triple Strecker reactions were unsuccessful.

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