Phosphonates synthons for the synthesis of phosphonates derivatives showing better bioavailability

A compound of formula (I)

• wherein
• R represents
• a group of formula (1)
• wherein R1 represents H, a straight or branched (C1-C6) alkyl group or a —(CH2)m—R2 group with R2 selected from the group consisting of hydrogen, halogen, OH, N3, NH2, epoxy groups, leaving groups and carbonyl groups and m is an integer from 0 to 5,
• represents a double or a triple bond,
• p being equal to 0 when is a triple bond and equal to 1 when
• is a double bond or,
• R=R2 with R2 selected from the group consisting of hydrogen, halogen, OH, N3, NH2, epoxy groups and analogs, leaving groups, leaving groups involved into a transmetalation step catalyzed by Pd(0), and carbonyl groups,
• n is an integer from 0 to 5
• X and Y independently of each other represent hydrogen, halogen or a straight or branched (C1-C6)alkyl group or an hydroxymethyl group, and
• R′ and R″ independently of each other
• represent a group selected from the group consisting of
• an oxymethylcarbonyl group of formula (2)
• wherein
• R1 and R′1 are independently of each other hydrogen or (C1-C4)alkyl group and
• R′2 is a straight or branched (C1-C6)alkyl group or straight or branched (C1-C6)alkoxy group
• with the proviso that when R is cis-propenyl
• n=0 and R′2 is methyl, then R1 and R′1 are not simultaneously hydrogen,
• a thioethylcarbonyl group of formula (3)
• wherein
• R3 is a straight or branched (C1-C6) alkyl group
• a lipohilic chain selected from the group consisting of hexadecyloxypropyl (HDP)-, octadecyloxyethyl-, oleyloxypropyl-, and oleyloxyethyl-esters with the proviso that when n=0 then R is not the cis-propenyl
• or
• R′ and R″ form with the phosphate atom to which they are linked a cycloalkyle group of formula (4)
• wherein R4, R5, R6, and R7 each independently represent a straight or branched (C1-C6)alkyl or aryl group or R4 and R7 independently represent a straight or branched (C1-C6) alkyl or aryl group or R5 and R6 form together an aromatic ring, said aromatic ring being optionally substituted
• with the proviso that
• are excluded.