Expanding the chemical diversity of spirooxindoles via alkylative pyridine dearomatization

Abstract

A mild and practical synthesis of spirooxindole [1,3]oxazino derivatives from N-substituted isatins and 1,3-dicarbonyl compounds with pyridine derivatives is reported. The reactions provided good to excellent yields. Further exploration of the molecular diversity of these compounds is demonstrated through Diels-Alder reactions.

Keywords: 1,3-dicarbonyl compounds; Diels–Alder reaction; chemical diversity; molecular diversity; pyridine dearomatization; spirooxindole.

Scheme 1

Unexpected alkylative pyridine dearomatization during our previous work on the synthesis of spirooxindole pyranochromenediones.

Figure 1

X-ray crystal structure of compound 6b.

Figure 2

X-ray crystal structure of compound 3d.

Scheme 2

Application of spiro [1,3]oxazino compound 3a in D–A reactions.

Figure 3

X-ray crystal structure of compound 8a.