Synthesis of Substituted β-Functionalised Styrenes by Microwave-Assisted Olefin Cross-Metathesis and Scalable Synthesis of Apremilast

Preparation of diversely substituted β-functionalised styrenes by microwave-assisted olefin cross-metathesis (CM) is described. This method can be also employed in the synthesis of β-deuterated α,β-unsaturated sulfones from inexpensive allylbenzenes, though unprecedented one-pot isomerisation/deuteration/cross-metathesis sequence. One of such obtained CM products has been utilised in a new scalable synthesis of Apremilast (6), a potent and orally active phosphodiesterase 4 and tumour necrosis factor-α inhibitor. The same strategy was used in synthesis of an optical antipode of 6, ent-Apremilast.