Callosobruchic acid

This synthesis has been adapted to make the natural (5 -isomer of 114, reducing the initially formed aldehyde to (S)-114 with baker s yeast. [This same synthesis has been adapted to make (S)-callosobruchic acid (115), see below]. Julia s synthesis of a-geraniol (73) was also extended to make 114 by hydro-boration. Hydroboration of 73 with diisopinocampheylborane (made from (- )-a-pinene [(-)-116]) gave only a small ee however. A synthesis of ( )-114 started with the reaction of 2-methylpropiolactone and the ethylene acetal of 3-oxobutylmagnesium bromide. The methyl ester of the acid 117 thus prepared was chain-lengthened by reaction with acetylene and rearrangement with a vanadium catalyst of the ynol thereby obtained. The aldehyde 118 was then reduced with lithium aluminum hydride to 114. ... 

The diacid corresponding to 114 is callosobruchic acid (115), and forms part of the copulation release pheromone of the azuki bean weevil, Callosobruchus chinensis Both chiral isomers have been synthesized by Mori et al. from methyl geranate epoxide (123). After scission of the epoxide group, the iodide 124 was made conventionally, then the chiral group was introduced using the Evans (R)- or (5)-prolinol propionamide enolate anion (125) (made with lithium diethylamide in tetrahydrofuran on the amide). Removal of the proline group... 

---