Bromomethyl 4-methoxyphenyl ketone → 2-(5-Benzyloxy-2-vinylphenoxy)-1-(4-methoxyphenyl)ethanone

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Reaction Steps

7-Benzyloxy-3-(4-methoxyphenyl)-2H-1-benzopyran can be prepared according to the following reaction scheme and protocols. Referring to Scheme 1,4-benzyloxy-2-hydroxybenzaldehyde (compound 1) was reacted with a mixture of methyl triphenyl phosphonium bromide (MTPPB) and potassium tert-butoxide (t-BuOK), followed by reaction with 2-bromo-4′-methoxyacetophenone to give 2-(5-benzyloxy-2-vinylphenoxy)-1-(4-methoxyphenyl)ethanone (compound 2a), which was subsequently reacted with a mixture of MTPPB and t-BuOK to give 4-benzyloxy-2-[2-(4-methoxyphenyl)allyloxy]-1-vinylbenzene (compound 2). Reaction of compound 2 with Grubbs' catalyst (II) gives 7-benzyloxy-3(4-methoxyphenyl)-2H-1-benzopyran (compound 3).

Provenance & Evidence