Patent ID: 7652172

Claim:
A method to synthesize protected DPD which comprises a) reacting gluconic acid γ-lactone with dimethoxycyclohexanone for a time and under conditions to produce 5,6-O-cyclohexylidene-glucono-1,4-lactone; b) subjecting said lactone to oxidative cleavage to produce 2,3-O-cyclohexylidene-glyceraldehyde; c) halogenating said glyceraldehyde under conditions to produce 1,1-dihalo-3,4-cyclohexylidenedioxybut-1-ene (“dihaloalkene”); d) purifying said dihaloalkene and further reacting said dihaloalkene under conditions to convert the alkene moiety of said dihaloalkene to an alkyne anion; e) quenching said anion with either i) a methylating agent to produce 1,1-dihalo-3,4-cyclohexylidenedioxypent-3-yne, or ii) water to produce 1,1-dibromo-3,4-cyclohexylidenedioxybut-3-yne, followed by methylation to produce 1,1-dibromo-3,4-cyclohexylidenedioxypent-3-yne, and recovering said alkyne; f) oxidizing said alkyne in non-aqueous solution under conditions to produce 4,5-cyclohexylidenedioxy-2,3-pentadione, which is said protected DPD; and g) recovering said protected DPD.