Methoxymethyl phosphine oxide

When the ylid derived from the oxide 7 was treated with benzaldehyde, a 2-methoxy-l,3-diene was formed. This led us to attempt a synthesis of (i) ar-turmerone by a sequence (Scheme 3) in which 7 effectively acts as an acyl anion equivalent. The required aldehyde 8 was synthesized in good yield using initially diphenyl(methoxymethyl)phosphine oxide (3), and then chlorotri-methylsilane-sodium iodide (12) to cleave the enol ether. 

WITTIG-HORNER REAGENTS Diethyl 2,2-dichloro-l-ethoxyvinyl phosphate. Diethyl methoxyefhoxymethylphos-phonate. Dimethyl 3-bromo-2-ethoxy-propenylphosphonate. Methoxymethyl-(diphenyl)phosphine oxide. 

Tri-p-tolylphosphine refluxed several hrs. with 10%-excess monodiloromethyl ether in benzene, and the resulting dhloride treated with Na-fluoroborate soln. in water (methoxymethyl)tris-(p-tolyl)phosphonium fluoroborate (Y 91%) added to nitryl fluoroborate and sulfolane, heated 6 hrs. at 110, pyridine hydrochloride added, and stirred 2 hrs. at 115° tris-(3-nitro-4-methylphenyl)phosphine (Y 51%). - Phosphonium salt formation protects the phosphorus from oxidation. F. e. s. G. P. Schiemenz and K. Rohlk, B. 104, 1219 (1971). 

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