Tetrahydrofuran → 6,7-Dihydro-2-methyl-5-methylenebenzo(b)furan-4(5H)-one

Beteiligte Stoffe

Reaktionsschritte

To a solution of the furanone of Step A (164.5 g/1.10 mole) in about 400 ml THF was added, in four separate portions, N-methylanilium trifluoroacetate (TAMA) (243 g) and trioxymethylene (99 g) over 31/2 hours, and the mixture refluxed for 20 hours. The mixture was cooled and partitioned between Et2O and water, the layers separated and the aqueous layer was extracted twice with Et2O. The combined Et2O layers were washed exhaustively with water, with NaHCO3 and then with brine, dried over MgSO4 and conc. in vacuo to yield an amber oil. This oil was flash chromatographed on silica gel using CH2Cl2 as solvent in several runs of 10-20 g per run. Fractions containing the fast moving material were combined, concentrated in vacuo to obtain the desired product as a yellow oil.

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