One-pot Synthesis of 1-Amidoalkyl-2-naphthols under Solvent-free Conditions

Compounds bearing 1,3-amino-oxygenated functional groups are present in a variety of biologically important natural products and potent drugs including a number of nucleoside antibiotics and HIV protease inhibitors, such as ritonavir and lipinavir.1–4 1-amidoalkyl2-naphthols can be easily hydrolyzed to 1-aminoalkyl-naphthols, which show biological activities such as hypertensive and bradycardiac effects.5–11 In multi-component reactions (MCRs), one can create highly complex molecules in a single reaction from readily available starting materials often without purification; thus, MCRs are time-effective and economically favorable processes in diversity generation.12,13 We previously reported the in situ generation of ortho-quinone methides (o-QMS) which further combine with β-naphthols to give 14H-dibenzo[a,j]xanthene derivatives.14,15 The present report describes the reaction of o-QMS with other nucleophiles such as amides for the synthesis of 1-amidoalkyl-2-naphthol derivatives (Scheme 1).