Selenium-promoted conversion of .beta.-diketones and .beta.-keto esters into .alpha.,.alpha.-dimethoxy .beta.-diketones and .alpha.,.alpha.-dimethoxy .beta.-keto esters
Selenium-promoted conversion of .beta.-diketones and .beta.-keto esters into .alpha.,.alpha.-dimethoxy .beta.-diketones and .alpha.,.alpha.-dimethoxy .beta.-keto esters