Mn(OAc)₃ catalyzed intermolecular oxidative peroxycyclization of naphthoquinone

Abstract

Manganese(III) acetate-mediated peroxycyclization between 2-hydroxy-3-methylnaphthoquinone and various alkenes was performed to obtain dihydronaphtho[2,3-c][1,2]dioxine-5,10(3H,10aH)-diones. The reactivity of symmetrical or unsymmetrical 1,1-disubstituted alkenes and monosubstituted alkenes allowed the synthesis of more than 50 original molecules. Focusing on the excellent reactivity of 2-hydroxy-3-methylnaphthoquinone, we describe the first example of Mn(OAc) 3 reactivity with nitrosubstituted alkenes. The scope, limitations and stereochemistry of the products synthesized are discussed. Starting from monosubstituted alkenes, the instability of a pair of diastereoisomers was observed, leading to ring opening.

Methyl 6-Benzyl-3-Hydroxy-3,6-Dimethyl-1,2-Dioxane-4-Carboxylate

“…The yield obtained in the open vessel was 36%; however, when we tried the O 2 atmosphere protocol (typically used for alkyl-oriented derivatives), the yield dropped to 7%. This result is in line with observations from previous studies on aryl derivatives, where reactions under a pure oxygen atmosphere resulted in lower yields of 1,2-dioxane [3,12].…”

“…The stereoselectivity of this reaction has been previously investigated: the hydroxyl group at C3 and the carbomethoxy at C4 consistently adopt a fixed 3,4-cis stereo relationship regardless of the alkene derivative employed (aliphatic or aromatic, symmetric or asymmetric) [5,11,12]. As anticipated, our reaction with an asymmetrically disubstituted alkene yielded only two of the four possible diastereoisomers.…”

“…The reactivity of alkyl and aryl alkenes varies significantly in Mn(III)-mediated oxidative cyclization. Phenyl derivatives, such as 1,1-diphenylethylene, exhibit higher reactivity due to the better stability of the tertiary carbon radical conjugated with two phenyl groups [3,5,12]. A comparison of the yields obtained with those reported in the literature revealed an intermediate reactivity of the alkene (2-methylallyl)benzene.…”

Advances in the synthesis of 1,2-dioxolanes and 1,2-dioxanes

“…119 Other heterocycles such as hydroxybenzoquinone 110 led to similar reaction product 111 (Scheme 11). 120 Tetronic acid 112, because of its prominent enol form, was also a very convenient substrate for such a transformation and 1,2-dioxanol 113 was isolated with an excellent yield (Scheme 14). 121…”