The Homologous "Silyl-Stobbe-Reaction" The single, twofold and mixed organooxyalkylation of glutaric anhydride is achieved by reaction of 2,6-bis(trimethylsiloxy)-4H -pyran (1) with acetals and ortho esters 2 or carbonyl compounds 5 and 7 to yield the 2,4-bis[1-(organooxy)alkyl]glutaric anhydrides 4,6,11a,12a or the 3,4-dihydro-6-trimethylsiloxy-3-[1-(organooxy) alkyl]-2H-pyran-2-ones 8-10.