Nonactic acid methyl ester

In contrast, cyclization of the carbonate derivative (5) of 2 with potassium hydride in THF/HMPT proceeds with inversion at C to provide ( —)-6, which on hydrogenation provides the methyl ester of (-I-)-nonactic acid (7). 

Substitution reaction with 2-acetonylfurane. A synthesis of nonactic acid ester (4), a budding block of the macrotetrohde nonactin, involves the reaction of 2-acetonylfurane (1) with Eschenmoser s reagent (2). The resulting unstable aldehyde (b) is immediately oxidized and then esterified to give (3). This is converted into the methyl ester of nonactic acid (4) in two steps. ... 

Ireland recognized early on the potential for the Claisen rearrangement in the synthesis of furan and pyran containing natural products. In 1980 Ireland and Vevert published the syntheses of both (-)- and (+)-nonactic acid using the Claisen rearrangement to establish the C2,C3 stereocenters (Scheme 4.111). Rearrangement of the S-silyl ketene acetal via the boat transition state afforded the methyl ester with an 86 14 diastereoselectivity [104]. 

Batmangherlich and Davidson (35) also resolved racemic methyl nonactate by chromatographically separating its esters 167 and 168 with (S)-O-acetylmandelic acid (36). 

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