Starting from cyclopentadiene,both dl-15-methyl-prostaglandin(ⅩⅤ) F_2α and its 15(R,S)-15-methyl ether(X_b) have been synthesized Ⅵa a ten-step process.The key reaotion steps involved in this synthesis were the use of the 15-methyl-containing aluminium oompound(Ⅳ_b)as a reagent to prepare Ⅵ_b(R₃=H),and the transformation of the tetraol monomethyl ether(ⅩⅠ_b)(R₃=H) to the known diol lactone(Ⅶ) in the presence of a platinum catalyst through selective oxidation by molecular oxygen with simultaneous demethylation.The reactions of various aluminium reagents(Ⅳ_c、Ⅳ_e)with V(R₃=H)were studied.Attempted demethylations of Ⅵ_b(R₃=C₆H₅CO-) with BF₃(C₂H₅)₂O at -78° and with boron trifuoride etherats-acetic anhydride at -18° did not give the expected results.