Reaction of glycine methyl ester (19) with imidate 18 under carefully optimized conditions allowed preparation of the rather unstable imidazolinone 11 in ca. 90% yield. Reaction of 11 with POCl(3)/DMF followed by aqueous workup gave aldehyde 2, a key intermediate for the synthesis of the angiotensin II antagonist Losartan, in ca. 55% yield. Structural identification of intermediates and byproducts formed during both the reaction to prepare 11 and the reaction of 11 with POCl(3)/DMF allowed development of several closely related syntheses of aldehyde 2.
A ncw route to L-carnitine (1) based on the resolution of the triniethylanimoniuni derivative 5 is described. The enantiomeric purity of 1 is determined by 'H-NMR of its 0-acetyl hydrochloride 11 using [Eu(hfc),] aschiral shift reagent. The optical rotation of 1 with an enantiomeric purity > 99 'YO is [a]:: = -31.3" (r = 10, H,O).
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