A-Acetyl-y-butyrolactone

Pyrano-fused heterocycles, namely pyrano[3,2-f]quinoline-2,5(6//)-diones, pyrano[3,2-f]benzopyran-2,5(6//)-dione, and pyrano[3,2-f]pyridine-2,5(67T)-diones, have been efficiently prepared by the condensation of 4-hydroxy-2-(l//)-quinolines, 4-hydroxycoumarin, or 4-hydroxy-(17/)-pyridone with a-acetyl-y-butyrolactone or the sodium salt of a-formyl-y-butyro-lactone in the presence of ammonium acetate <1999JHC467>. 

Reaction of the aminoguanidine 166 with either /3-ketoesters or a-acetyl--y-butyrolactone produced the triazolopyrimidine derivatives 167 and 168, respectively [82JAP(K)57/175193] (Scheme 32). 

The starting material for preparation of the reagent is a-acetyl-y-butyrolactone (1), available from U. S. Industrial Chemicals. One patented route to (1) is that... 

Using a-acetyl-y-butyrolactone as the carbonyl component in the Fischer synthesis, decarboxylation occurs and it is thus possible to prepare a 1,2-disub-stituted indol-3-ylethanol [2637]. In a related reaction, a y-haloaldehyde or a y-haloketone reacts with an arylhydrazine to give a tryptamine in which the side-chain nitrogen is derived from the terminal nitrogen of the reacting phenylhydrazine this and related reactions were reviewed in 1974 and 1988 [2641,3461). The course of Fischer indolization of the preformed monophenyl-hydrazone of cyclohexane-1,3-dione changes when the reaction is allowed to proceed under conditions which encourage ketal formation [2565]. 

Corresponding runs beginning with 128 g. (1 mole) of a-acetyl-y-butyrolactone gave 107-112 g. (89-93%) of crude 5-chloro-2-pentanone. The checkers consistently obtained yields of 79-81% using U. S. Industrial Chemicals, Inc., lactone. 

Finally, reaction20 of compound 30 with a-acetyl-y-butyrolactone (43) affords two isomeric pyrrololl,2-a]pyrimidine derivatives (44 and 45) Eq. (12)1. 

Condensation of 3-(2-amino-4-thiazolyl)comnarin 91 with a-acetyl-y-butyrolactone in a mixture of polyphosphoric acid and POCI3 afforded thiazolo[3,2-a]pyrimidin-5-one 92, while condensation of 91 with P-keto esters gave 7-methyl-3 -(2-oxo-2H-chromen-3 -yl)-5 H-[ 1,3]thiazolo [3,2 -a]pyrimidin-5 -ones 93(Scheme 42). Reaction between 91 and diethyl 2-(methoxymethylene)malonate imder solvent-free conditions yielded 3-(2-oxo-2H-chromen-3-yl)-5-oxo-5H[l,3]thiazolo[3,2-a]pyrimidine-6-carboxylate 94 [67],... 

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