Transformation of Amino Acids into Nonracemic 1‐(Heteroaryl)ethanamines by the Enamino Ketone Methodology |
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Authors: | Samo Pirc,David Bevk,Amalija Golobi
,Branko Stanovnik,Jurij Svete |
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Affiliation: | Samo Pirc,David Bevk,Amalija Golobič,Branko Stanovnik,Jurij Svete |
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Abstract: | N‐Protected L ‐phenylalanines 1a,b were transformed, via the corresponding Weinreb amides 2 and ethynyl ketones 3 , into chiral enamino ketones 4 (Scheme 1). Similarly, L ‐threonine 6 was transformed in four steps into the enamino ketone 10 . Cyclocondensations of 4 and 10 with pyrazolamines 11 , benzenecarboximidamide ( 12 ), and hydrazine derivatives 18 afforded N‐protected 1‐heteroaryl‐2‐phenylethanamines 15a – e, 16, 17 , and 21a – k and 1‐heteroaryl‐1‐aminopropan‐2‐ols 23a,b in good yields (Schemes 2 and 3). Finally, deprotection by catalytic hydrogenation furnished free amines 22a – g and 24a,b (Scheme 3). |
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Keywords: | Amino acids Ketones, enamino Amines, chiral Cylization recations Ethanamines |
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