3a. The former lactone has been prepared by a multistep asymmetric synthesis3 and an optical res~ lution.~ The latter lactone can be obtained by an enzymatic transformation of 4- hydroxy-2-methylbut-2-en-l-al ethylene acetal, 5 an asymmetric synthesis, 6 and an optical resolution from its dl form. 7 However, these conventional methods are not feasible for a large-scale production of 3a. As part of our research program on the conversion of readily ...
