Abstract
Reaction of 1, 3-dioxo- or 1, 4-dioxo-1, 2, 3, 4-tetrahydroisoquinolines (Ia, b, c) with ketenethioacetals (IIa, b, c, d, e, f) gave the corresponding substitution products (IIIa, b, c, d, e, f, IVa, b, V, VI, VII, IX, X) of methylthio group in ketenthioacetal derivatives in a good yield. The application of these reactions afforded pyrano [2, 3-c] isoquinoline and pyrrolo [1, 2-b] isoquinoline derivatives. The reaction of IIIa, b, IVa, or IVb with amines afforded recyclized products, 2-benzopyrano [3, 4-b] pyridine derivatives (XIIIa, b, c, d). The reaction of VII and IX with amines gave amino derivatives (XVIa, b, c) which were the replaced products of methylthio groups of VII and IX. The reaction of X with aminoacetal afforded an aminoacetal derivative (XVII) which was treated with hydrochloric acid to give a cyclized product (XVIII). The reaction of IX or XVIc with ethyl orthoformate or formic acid gave pyrimidine derivatives (XXa, b, XXI).
