Synthesis and chemical reactivity of indenoisoxazoles

Abstract

Treatment of 2‐pivaloyl‐1,3‐indandione (1) with hydroxylamine under acidic conditions, results in formation of 8‐t‐butylindeno[1,2‐c]isoxazol‐7‐one (2) while treatment of the triketone with hydroxylamine at neutral or basic pH gave 6 which upon cyclization gave the isomeric 3‐t‐butylindeno[1,2‐c]isoxazol‐4‐one (7). Compound 7 was readily reduced to amine 12 by treatment with hydrazine or hydrogen over platinum. The amine, although quite unreactive, was converted to 3‐t‐butylindeno[1,2‐c]pyrazol‐4‐one (13) with hydrazine or reduced to 15 and 16 with sodium in liquid ammonia and alcohol. Surprisingly, the amine 3 obtained from isoxazole 2 gave reduction product 15 from a sodium‐liquid ammonia reduction and not the expected product 18. Spectral evidence for each of the structures is discussed.

Highly Diastereoselective One-Pot Synthesis of Spiro{cyclopenta[a]indene-2,2‘-indene}diones from 1-Indanones and Aromatic Aldehydes

“…Reaction of indanone 2 with benzaldehyde ( 3g ) under conditions of method A also afforded some spirocompounds but in moderate to low yields [ 7g 3f (32% yield) + 9g 3f (9% yield)]; in this case the enone 5g 3a was the main reaction product (42%) (Table , entry 27). As observed in the 5,6-dimethoxy series, reaction of 2 with pivalaldehyde furnished exclusively the enone 5h , although in higher yield (68%) (Table , entry 29).…”