Ketals acetone dimethyl ketal

Acetonecarboxylic acid, a24 Acetone cyanohydrin, hi38a Acetone dimethyl acetal, d519 Acetone ketal of glycerin, d599 Acetonylacetone, h60... 

Other related reactions involve TV-fluorenylmethyloxycarbonyl (N-Fmoc) AAs and aliphatic aldehydes (83JOC77) or substituted /-butoxycarbonyl (N-Boc) Aas and 2,2-dimethyoxypropane (acetone dimethyl ketal) (84TL5855 87JOC2361 88TL2019), as well as A-(dimethylthio)methylene derivatives of an AA and aromatic aldehydes [89JCS(P1)1577]. 

The most important and widely used ketal is the acetonide. It is prepared by the reaction of the diol with acetone " or acetone dimethyl acetal and an acid catalyst. Also 2-alkoxy and 2-silyloxy propenes can be applied for this purpose (Scheme 49). ° In the reactions with carbohydrates fiiranose rings are formed if possible, but under kinetically controlled conditions also 1,3-dioxanes may be constructed. In the cases of hexoses which do not contain cw-l,2-diols the reaction usually involves toe 6-OH group. 

Cyclic ketals by transacetalation 0,0 Isopropylidene derivatives of carbohydrates with acetone dimethyl ketal... 

Methyl esters s. 18, 935 with acetone dimethyl ketal as water scavenger, f. methods, s. H. Liliedahl, Acta Ghem. Scand. 20, 95 (1966)... 

Startg. m. refluxed in a mixture of acetone and acetone dimethyl ketal containing p-toluenesulfonic acid with a Dean-Stark trap filled with molecular sieves product. Y 96%. F. e. s. G. Just et al.. Can. J. Chem. 53, 131 (1975). 

A suspension of 8-azaguanosine in acetone containing acetone dimethyl ketal to maintain anhydrous conditions and di-p-nitrophenyl hydrogen phosphate stirred ca. 1 hr. until soln. is complete, and the product isolated after an additional 3 hrs. 2, 3 -0-isopropylidene-8-azaguanosine. Y 90%. F. e. s. A. Hampton, Am. Soc. 83, 3640 (1961). 

Water scavenger, acetone dimethyl ketal as — 17, 231 ----, ethyl propionate as —... 

Acetone dimethyl ketal added during 1.5 hrs. at 110-120° to a stirred soln. of succinic anhydride and benzoic acid in pyridine-diglyme with distillation of the product during ca. 2 hrs. 2-methoxypropene. Y 95%. F. e. s. M. S. Newman and M. C. Vander Zwan, J. Org. Chem. 38, 2910 (1973). 

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