A diastereospecific synthesis of α-amino-β- hydroxycyclohexenecarboxylic acid (7) was found starting from 4- chloromethylene-5(4H)-oxazolone (1) which reacted with 2,3-dimethylbutadiene in the presence of EtAlCl2. The Diels-Alder reaction gave two diastereoisomeric cycloadducts 2 and 3, depending on the configuration of the starting dienophile 1. Compounds 2a and 3 were transformed into the ester 4 and the oxazoline 6, respectively, by reaction with MeOH and p-TSA. The reaction of 2a and 3 with dimethylamine in ethanol solution gave the corresponding amides 8 and 9, respectively, which were transformed into the bicyclic oxazoline 10 on reaction with Na2CO3 in acetonitrile. On acidic hydrolysis both oxazolines 6 and 10 were transformed into α-amino-β- hydroxycyclohexenecarboxylic acid (7) that includes the serine skeleton.
A highly diastereoselective approach to conformationally constrained serine analogues: Synthesis of an α-amino-β-hydroxycyclohexenecarboxylic acid and derivatives / F. Clerici, M.L. Gelmi, A. Gambini. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 64:16(1999), pp. 5764-5767. [10.1021/jo9821877]
A highly diastereoselective approach to conformationally constrained serine analogues: Synthesis of an α-amino-β-hydroxycyclohexenecarboxylic acid and derivatives
F. ClericiPrimo
;M.L. GelmiSecondo
;
1999
Abstract
A diastereospecific synthesis of α-amino-β- hydroxycyclohexenecarboxylic acid (7) was found starting from 4- chloromethylene-5(4H)-oxazolone (1) which reacted with 2,3-dimethylbutadiene in the presence of EtAlCl2. The Diels-Alder reaction gave two diastereoisomeric cycloadducts 2 and 3, depending on the configuration of the starting dienophile 1. Compounds 2a and 3 were transformed into the ester 4 and the oxazoline 6, respectively, by reaction with MeOH and p-TSA. The reaction of 2a and 3 with dimethylamine in ethanol solution gave the corresponding amides 8 and 9, respectively, which were transformed into the bicyclic oxazoline 10 on reaction with Na2CO3 in acetonitrile. On acidic hydrolysis both oxazolines 6 and 10 were transformed into α-amino-β- hydroxycyclohexenecarboxylic acid (7) that includes the serine skeleton.Pubblicazioni consigliate
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