Spirobipyridopyrans, spirobinaphthopyrans, indolinospiropyridopyrans, indolinospironaphthopyrans and indolinospironaphtho-1,4-oxazines: synthesis, study of X-ray crystal structure, antitumoral and antiviral evaluation Original Research Article

The novel racemic indolinospirobenzopyrans (5–7), indolinospironaphthopyrans (11–14) and indolinospironaphtho-1,4-oxazine (17) were synthesized by an aldol type of condensation of 1′,3′,3′-trimethyl-2 ′-methyleneindoline and its 5-substituted derivatives with an appropriately substituted hydroxybenzaldehyde, hydroxynaphthaldehyde or nitrosonaphthol. An unequivocal proof of the stereostructures of 9 and 17 was obtained by the single-crystal X-ray diffraction method. A substituted indoline ring and the benzopyran ring in 9 and the naphtho-1,4-oxazine moiety in 17 are interconnected via the common chiral atom and positioned almost perpendicularly to each other. The five-membered 2,3-dihydropyrrolo moiety of the indoline ring adopts an envelope conformation in both structures. Of all the compounds of this series, spirobipyridopyran (1) inhibited specifically the growth of human melanoma (HBL) (IC50: 0.9 μM) cells but not the growth of normal fibroblasts (WI38). Indolinospirobenzopyrans (8–10) showed significant cytostatic activities against all tumor cell lines. However, these compounds also exhibited a cytotoxic effect on normal human fibroblasts. The indolinospirobenzopyrans 4, 6–8, 10 and the indolinospironaphtho-1,4-oxazine 16 showed, albeit modest, selectivity as antiviral agents against varicella-zoster virus (VZV) and/or cytomegalovirus (CMV) (EC50 within the concentration range of 1.0–12.6 μM).