Claisen-Schmidt condensation reaction of 1,4-cyclohexanedione monoethyleneketal (1) with p-methoxybenzaldehyde, under base catalyzed conditions, has afforded 7,9 bis (4-methoxybenzylidene)-1,4-dioxaspiro[4,5]decan-8-one (2). The bis-benzylidene 2 was functionalized with some selected organophosphorus reagents. Thus, compound 2 was reacted with tris-(dialkylamino) phosphines 3a,b, in refluxing toluene and in presence of a catalyst, to give a products mixture of the corresponding oxaphospholedioxolane oxides 8a,b and tetraalkylphosphonicdiamides 9a,b. Moreover, the reaction of bis-benzylidene 2 with the trialkylphosphite reagents 4a,b afforded the corresponding alkyl- phosphonate derivatives 10a,b. The phosphonate 10b could be also obtained upon reacting bis-bezylidene 2 with diisopropylphosphite (5) under the same experimental conditions. The reaction of bis-benzylidene 2 with the stable phosphoniumylides, namely, (carbmethoxymethylene)-, or (carbethoxymethylene) -triphenylphosphorane (6a,b) , afforded the dihydrospiroindenedioxolanone derivative 11 under the given reaction conditions. Moreover, compound 11 was also obtained from reactions of the dialklyphosphonoacetate Wittig-Horner reagents 7a,b with compound 2. On the other hand, reaction of diethyl(cyanomethylene) phosphonate 7c with bis-bezylidene 2, in an ethanolic sodium ethoxide solution, gave the 1,4- dispiroylidene acetonitrile derivative 12. Possible reaction mechanisms are discussed and the structures of the new products are confirmed from their analytical and spectroscopic data. The antimicrobial activity of the synthesized compounds was also investigated.