Synthesis and Reactions of .alpha.-(Trifluoromethanesulfonyloxy) Enecarbamates Prepared from N-Acyllactams

Abstract

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

Zinc(II) Catalyzed Conversion of Alkynes to Vinyl Triflates in the Presence of Silyl Triflates

“… 1 These intermediates are usually produced by trapping ketone enolates with various trifluoromethanesulfonylating agents. 2 Fewer methods exist for their formation from alkynes. Early efforts involved the addition of trifluoromethanesulfonic acid (triflic acid) to an alkyne.…”

New Derivatives of Levoglucosan by Tandem Epoxide Allyl Alcohol Rearrangement‐Cuprate Cross‐Coupling

“…Such reactions are only known for the much more reactive vinyl triflates. [31][32][33] Possibly, anchimeric assistance facilitates the substitution of the tosyl group, as indicated in Scheme 2, supported by the usual coordination of the copper to the double bond, as known from alkenylation or arylation with Gilman cuprates. [31] This view of the two-step mechanism was supported by the conversion of the allyl alcohol intermediate 5, isolated in one case in the corresponding reactions with the ethyl cuprate, to the substitution product 6a under the same reaction conditions used for conversion of 3 to 6a (Scheme 2).…”

Chemistry of Lactam-Derived Vinyl Phosphates: Stereoselective Synthesis of (+)-Fagomine

“…After filtration and evaporation of the solvent (without heating and leaving a small volume of solvent), the crude phosphate was chromatographed (EtOAc-n-hexane, 1:2, +1% Et 3 N, R f = 0.26) on a short layer of SiO 2 (3.5 cm of SiO 2 in a column with internal diameter of 3 cm) to give 9 (1.044 g, 85%) as a pale yellow oil. 1 (d, 4 C), 129.5 (s), 129.1 (d, 2 C), 125.5 (d, 2 C), 120.0 (d, 4 C), 113.8 (d, 2 C), 98.8 (d), 69.7 (d), 68.5 (t), 55.3 (q), 53.3 (q), 42.8 (t), 29.7 (t). MS: m/z = 525 (1) [M + ], 121 (100).…”

“…The palladium-catalyzed alkoxycarbonylation of lactamderived vinyl triflates 1 and phosphates 2 has been effectively applied in the past to the synthesis of several natural compounds. 3 We have recently included such a reaction in a synthetic sequence to efficiently obtain enantiopure (2S,4R)-4-hydroxypipecolic acid from commercially available ethyl (3S)-4-chloro-3-hydroxybutanoate.…”