Synthesis of a tetrahydropyrano[2,3-d]oxazole analogue of trehazolin

Tetrahydropyrano[2,3-d]oxazole 6 as an analogue of trehazolin was synthesized from compound 3, which is a protected 1,3-bis(β-d-glucopyranosyl)thiourea. In contrast, compound 10, a protected 1,3-bis(α-d-glucopyranosyl)thiourea, and 15, a mixed species having one α-d-glucopyranosyl group and one β-d-glucopyranosyl group, did not yield the corresponding pyranooxazolines as anticipated, giving instead, respectively, a furo[2,3-d]oxazole 14 and a complex mixture of unidentified products.