Site-selectivity control in hetero-Diels–Alder reactions of methylidene derivatives of lawsone through modification of the reactive carbonyl group: an experimental and theoretical study

Abstract

Selective monoacetalization of lawsone inverts the site-selectivity of the Diels–Alder reactions of its alkylidene derivatives favoring the protected β-lapachone derivatives.

Recent Advances in the Synthesis of 2-Hydroxy-1,4-naphthoquinone (Lawsone) Derivatives

“…Tsanakopoulou et al 77 conducted a study involving the synthesis, isolation, and utilization of an acetal derivative of lawsone 147 in tandem Knoevenagel/hetero-Diels–Alder reactions catalyzed by ( S )-proline (Scheme 48 ). This research aimed to explore the reactivity of hydroxyquinones, providing new insights and perspectives.…”

“…This resulted in the predominantly high-yield formation of pyrano-1,2-naphthoquinone (β-lapachone) derivatives, as well as the isomeric pyrano-1,4-naphthoquinone (α-lapachone) derivatives 151 – 154(a – d) (Scheme 49 ). 77…”

“…This resulted in the predominantly high-yield formation of pyrano-1,2-naphthoquinone (-lapachone) derivatives, as well as the isomeric pyrano-1,4-naphthoquinone (-lapachone) derivatives 151-154(a-d) (Scheme 49). 77 Scheme 49 Reactions of the in situ generated alkylidene-1,3-diones 149a-d with alkyl vinyl ethers 150…”