A stereoselective propargylation of propargylic acetates with substituted 2-naphthol derivatives in presence of a Cu(OTf)2 and chiral P,N,N ligand L system is reported. The chemodivergent reaction produces dearomatization (C-propargylayion) of 2-nahthols when C1-substitution is an electron rich group and etherification (O-propargylayion) takes place with an electron deficient group as C1-substitution. The dearomation reaction yielded substituted 2-naphthalenone derivatives with excellent control of chemo-, enantio- and diastereoselectivities (up to 99% ee, dr = 8:1) which bearing a vicinal quaternary-tertiary stereo-centre. Time dependent 1H NMR study revealed that ether formation (O-propargylation) followed by 1,3-sigmatropic shift might not be the mechanism of dearomatization (C-propargylation) reaction. The methodology is compatible with a wide range of functional groups, and is the first example of asymmetric propargylic dearomatization of 2-naphthols. Additionally, symbolic large scale reactions and related transformations of the dearomatized products disclose the potential synthetic utility of this protocol.

Chemodivergent, stereoselective propargylic deromatization and propargylic etherification of 2-naphthols

ACS Fall 2021

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