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US 5,349,095 AGranted
Process for preparing hydroxyalkylbenzocyclobutenes
AssigneeThe Dow Chemical Company
InventorsP. J. Thomas, R. Garth Pews
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AssigneeThe Dow Chemical Company
InventorsP. J. Thomas, R. Garth Pews
Estimating the term…
A process for preparing a substituted or unsubstituted 3- or 4-hydroxyalkylbenzocyclobutene compound comprises reducing a corresponding 3- or 4-formyl or ketobenzocyclobutene compound with a hydride at a temperature below that at which dimerization or oligomerization of the formyl- or ketobenzocycloutene compound or the thus-produced hydroxyalkylbenzocyclobutene compound is a significant side reaction, for a time sufficient to convert the formyl- or ketobenzocyclobutene compound to the hydroxyalkylbenzocyclobutene compound. In a two-step process, formylbenzocyclobutenes are prepared from bromobenzocyclobutenes in 90% yield or from benzocyclobutenes in a 70% yield, and then converted to hydroxymethylbenzocyclobutenes for an overall yield of about 85% from a bromobenzocyclobutene or of about 65% from a benzocyclobutene. In a two-step process, ketobenzocyclobutenes from bromobenzocyclobutene Grignard reagents and an N-alkanoyl- or N-aroyl-2-methylaziridine are converted to hydroxyalkylbenzocyclobutenes in high yields.
A process for preparing a substituted or unsubstituted 3- or 4-hydroxymethylbenzocyclobutene compound, comprising reducing a corresponding 3-or 4-formylbenzocyclobutene compound with a hydride selected from the group consisting of lithium aluminum hydride, sodium borohydride and NaBH.sub.3 CN at a temperature below that at which dimerization or oligomerization of the formylbenzocyclobutene compound or the thus-produced hydroxymethylbenzocyclobutene compound is a significant side reaction, for a time sufficient to convert the formylbenzocyclobutene compound to the hydroxymethylbenzocyclobutene compound, including the prior step of preparing a 3- or 4-formylbenzocyclobutene by reacting a substituted or unsubstituted 3- or 4-bromobenzocyclobutene compound with magnesium to produce a corresponding 3- or 4-benzocyclobutenyl magnesium bromide and treating the thus-formed 3- or 4-benzocyclobutenyl magnesium bromide with dimethylformamide to produce a corresponding 3- or 4-formylbenzocyclobutene compound.
A process for preparing a substituted or unsubstituted 3- or 4-hydroxymethylbenzocyclobutene compound, comprising reducing a corresponding 3-or 4-formylbenzocyclobutene compound with a hydride selected from the group consisting of lithium aluminum hydride, sodium boro-hydride and NaBH.sub.3 CN at a temperature below that at which dimerization or oligomerization of the formylbenzocyclobutene compound or the thus-produced hydroxymethylbenzocyclobutene compound is a significant side reaction, for a time sufficient to convert the formylbenzocyclobutene compound to the hydroxymethylbenzocyclobutene compound, including the prior step of preparing a 3- or 4-formylbenzocyclobutene by reacting a benzocyclobutene compound and dichloromethyl methyl ether in the presence of titanium tetrachloride to produce the 3- or 4-formylbenzocyclobutene compound.
Dependencies are inferred from the claim text.