Processes and intermediates for preparing substituted hexahydrofuro [2,3-b] furans

A compound having the formula

• wherein R1 is hydrogen or an OH protecting group, or is selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, heteroalkyl, heteroalkenyl, cycloheteroalkyl, cycloheteroalkenyl, aryl, heteroaryl, arylalkyl, and heteroarylalkyl, each of which is optionally substituted;
• R2 is alkyl, cycloalkyl, heteroalkyl, cycloheteroalkyl, arylalkyl, or heteroalkyl, each of which is optionally substituted;
• RP2 is hydrogen, hydroxyl protecting group or a pro -drug forming group;
• R3 is alkyl, heteroalkyl, cycloalkyl, cycloheteroalkyl, arylalkyl, or heteroarylalkyl;
• Ar is aryl is optionally substituted with a radical —(CH2)XZx, where x is an integer from 0-6 and ZX is selected from halogen, hydroxy, alkanoyloxy, optionally substituted aroyloxy, alkyl, alkoxy, cycloalkyl, cycloalkoxy, alkenyl, alkynyl, haloalkyl, haloalkoxy, halocycloalkyl, halocycloalkoxy, C1-C6alkylamino, (C1-C6alkyl)(C1-C6alkyl)amino, alkylcarbonylamino, N—(C1-C6alkyl)alkylcarbonylamino, aminoalkyl, C1-C6alkylaminoalkyl, (C1-C6alkyl)(C1-C6alky)aminoalkyl, alkylcarbonylaminoalkyl, N—(C1-C6alkyl)alkylcarbonylaminoalkyl, cyano, and nitro or ZX is selected from —CO2R4 and—CONR5R6, where R4, R5, and R6 are each independently selected in each occurrence from hydrogen, C1-C6alkyl, aryl-C1-C6alkyl, and heteroaryl-C1-C6alkyl;
• or Ar is 3,4-methylenedioxyphenyl;
• or Ar is heteroaryl which is optionally substituted;
• and
• wherein the compound is not