An operationally simple and metal-free cross-coupling of quinone monoacetals (QMAs) with 2-naphthols catalyzed by triflic acid is reported. This formal [3+2] annulation allowed the synthesis of diverse naphtho[2,1-b]benzofuran derivatives in moderate to good yields. Preliminary mechanistic studies reveal the initial nucleophilic substitution of QMAs with 2-naphthols in preference to the mixed acetal formation and subsequent [3,3] sigmatropic rearrangement.

We present a Lewis-acid-catalyzed (3 + 2)-cycloaddition of donor−acceptor cyclopropanes and selenocyanate (as its tetramethylammonium salt) for the synthesis of dihydroselenophenes. The transformation proceeded with moderate to excellent yields and showed a high functional group tolerance. Further oxidation using DDQ delivered selenophenes.

Althougha zaoxyallyl cations are widely used as 1,3-dipoles for various cycloaddition reactions leading to nitrogen-containing heterocycles, their application in higherorder cycloaddition reaction remains scarce.H erein, we present the [8+ +3]-cycloaddition reaction of tropones with in situ generated azaoxyallyl cations allowing the one-step con-struction of cycloheptatriene-fused 1,4-oxazinones in moderate to good yields. This base-promoted new carbon-oxygen and carbon-nitrogen bond-formingr eaction takes place under mild conditions in the absence of transition metal catalysts.Scheme1.[3+ +x]Cycloaddition reactions of azaoxyallyl cations and [8+ +3] cycloaddition using tropones.[a] Dr.Yellow oil, 0.074 gi n0 .5 mmol scale, 44 %y ield. R f (Pet. ether/ EtOAc = 80/20): 0.57; 1 HNMR (400 MHz, CDCl 3 ): d = 7.36-7.32 (m, 5H), 6.73-6.34 (m, 2H), 6.25-6.11( m, 1H), 5.98 (d, J = 6.7 Hz, 1H),

The reaction of 2-naphthols with aziridines in the presence of AgOTf resulting in a dehydrative, formal [3+2] annulation is reported. The reaction allows the synthesis of functionalized benzoindolines, and tolerates a broad range of functional groups. A preliminary study on the mechanism of this reaction indicates an S1-type ring-opening of aziridines. This method is demonstrated for the one-pot synthesis of benzoindoles.

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