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16.13.4.4.1 O/S-Functional Group Modification

DOI: 10.1055/sos-SD-016-00745

Kikelj, D.Science of Synthesis, (200416722.

The reaction of quinazoline-2,4(1H,3H)-dione (2) with chlorotrimethylsilane[‌919‌] or hexamethyldisilazane[‌921‌] affords 2,4-bis(trimethylsiloxy)quinazoline in high yield (Scheme 239). Although alkylation of quinazolin-4(3H)-ones (321, X=O) generally occurs at N3 (see Section 16.13.4.2.2.2) with the Claisen method,[‌965‌] using alkyl or aryl halides or dialkyl sulfate[‌801‌] and potassium carbonate in acetone or butanone, alkylation of quinazolin-4(3H)-ones produces the O-alkyl derivatives 322 (X=O) in good yields (Scheme 240).[‌683‌,‌793‌,‌800‌,‌801‌,‌966‌] Selective O-alkylation also takes place when a C2 substituent prevents alkylation at N3 through steric and/or electronic effects.[‌332‌,‌800‌] Methylation of quinazolin-4(3H)-one with diazomethane affords 4-methoxyquinazoline in 20% yield.[‌822‌] Alkylation of quinazoline-4(3H)-thiones 321 (X=S) with alkyl halides[‌811‌‌813‌,‌843‌,‌910‌,‌967‌] or dialkyl sulfates[‌814‌,‌815‌] usually takes place on the sulfur atom, giving the 4-(alkylsulfanyl) derivatives 322 (X=S) (Scheme 240). Similarly, quinazolin-4(3H)-ones react with Merrifield resin in dimethylformamide in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene to give the resin-supported quinazolines in excellent yields.[‌845‌]

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References


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