Substituted perhydrofuropyrans: easy preparation from 2-chloromethyl-3-(2-methoxyethoxy)propene through 3-methylene-1,6-diols

The reaction of 2-chloromethyl-3-(2-methoxyethoxy)prop-1-ene (1) with an ex cess of lithium powder and a catalytic amount of naphthalene (2.5%) in the presence of a carbonyl compound (E-1 =R-1 (RCO)-C-2) in THF at -78 to 0 deg rees C, followed by treatment with an epoxide [E-2=(RRC)-R-3-C-4(O)CHR5] at 0 to 20 degrees C leads, after hydrolysis, to the expected unsaturated dio ls 2. When some compounds 2 (2e-h) are successively hydroborated (BH3 . THF ) and oxidised (33% H2O2 and then PCC), the expected perhydrofuropyrans 3e- h are isolated directly. (C) 2000 Elsevier Science Ltd. All rights reserved .