6,8-Difluoro-2-tetralone → 2-(6,8-Difluoro-1,2,3,4-tetrahydro-naphthalen-2-ylamino)-pentanoic acid methyl ester

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Reaction Steps

Combine L-norvaline methyl ester-hydrochloride (1 equiv) with 6,8-difluoro-3,4-dihydro-1H-naphthalen-2-one (1 equiv) in methylene chloride and stir 30 min. and add sodium triacetoxy borohydride (1.1 equiv) and stir at rt overnight. The reaction is quenched with aqueous sodium bicarbonate, extracted with methylene chloride, dried, and concentrated. The resultant material is purified by silica gel chromatography to afford the separated diastereomers of 2-(6,8-Difluoro-1,2,3,4-tetrahydro-naphthalen-2-ylamino)-pentanoic acid methyl ester: Diastereomer 1; 13C NMR (100 MHz, CDCl3) 14.0, 19.4, 27.7, 28.2, 29.5, 29.6, 36.3, 51.1, 58.7, 100.7, 100.9, 101.2, 110.5, 110.7, 110.8, 118.5, 118.6, 141.1, 159.7, 159.8, 162.1, 176.7; MS m/z 298.3 (M+1). Diastereomer 2; Diagnostic 13C NMR (100 MHz, CDCl3) 14.0, 19.3, 28.3, 28.4, 28.5, 30.3, 36.4, 51.1, 52.0, 58.5, 100.7, 100.9, 101.2, 110.5, 110.7, 176.8; MS m/z 298.3 (M+1).

Provenance & Evidence