3,4-Difluorobenzylamine → [3-(4-Chloro-phenyl)-allyl]-(3,4-difluoro-benzyl)-amine

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Reaction Steps

The cis-diaryl compounds were prepared as shown above. To a solution of 4-chlorocinnamaldehyde (1.45 g, 8.70 mmol) in 100 mL of dichloroethane was added 3,4-difluorobenzylamine followed by sodium triacetoxyborohydride (3.7 g, 17.5 mmol, 2 eq.). The mixture was stirred overnight at room temperature, washed with aq. NaHCO3, brine, dried over MgSO4, filtered, concentrated and chromatographed with 40% ethyl acetate-hexanes to provide 0.84 g of [3-(4-chloro-phenyl)-allyl]-(3,4-difluoro-benzyl)-amine. The [3-(4-chloro-phenyl)-allyl]-(3,4-difluoro-benzyl)-amine was coupled with 5-(2,4-dichloro-phenyl)-penta-2,4-dienoyl chloride to provide 5-(2,4-dichloro-phenyl)-penta-2,4-dienoic acid [3-(4-chloro-phenyl)-allyl]-(3,4-difluoro-benzyl)-amide. When 5-(2,4-dichloro-phenyl)-penta-2,4-dienoic acid [3-(4-chloro-phenyl)-allyl]-(3,4-difluoro-benzyl)-amide was subjected to the Diels-Alder reaction conditions shown above, it gave 60 as the major product. Epimerization of the trans-lactam gave 61 and reduction of the double bond of 61 gave 62.

Provenance & Evidence