Since their discovery twenty years ago,1 vinyl trifluoromethanesulfonates (vinyl triflates) have been widely used as synthetic intermediates.2-6 Cross coupling of vinyl triflates with various organometallic compounds like organocopper, -aluminum, -stannane, -zinc, and -boron reagents under mild conditions and with high chemo-and stereoselectivity is an effective way to construct many organic molecules.2 These versatile intermediates can be easily prepared from the corresponding carbonyl compounds or enolates by treatment with triflic anhydride,7 TV,TV-bis(trifluoromethanesulfonyl)aniline,8 or TV-pyridyltriflimides.9 The preparation and reactivity of vinyl triflates from enolates of ketones, aldehydes, and lactones have been studied,2

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Pyridine‐derived triflating reagents: N‐(2‐pyridyl)‐triflimide and N‐(5‐chloro‐2‐pyridyl)triflimide product: N‐(2‐pyridyl)triflimide product: N‐(5‐chloro‐2‐pyridyl)triflimide

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The asymmetric synthesis of all four of the known natural phlegmarines and one synthetic derivative has been accomplished in 19 to 22 steps from 4-methoxy-3-(triisopropylsilyl)pyridine. Chiral N-acylpyridinium salt chemistry was used twice to set the stereocenters at the C-9 and C-2′ positions of the phlegmarine skeleton. Key reactions include the use of a mixed Grignard reagent for the second N-acylpyridinium salt addition, zinc/acetic acid reduction of a complex dihydropyridone, and a von Braun cyanogen bromide N-demethylation of a late intermediate. These syntheses confirmed the absolute stereochemistry of all the known phlegmarines.