Stereoselective reactions trifluoromethanesulfonic acid

The amidation of a-hydroxyallylic phosphonates (2IS) with nitriles in the presence of trifluoromethanesulfonic acid proceeds with high ( )-stereoselectivity and with moderate to good yields of (216) [R = H, R = Me or Ph R = Me, = Ph R R = (CH2)n, n = 2-4 R = Me or Ph]. Mannich reactions between diethoxyphosphinoylacetic acid, a primary amine, and formaldehyde, have been used for the preparation of (217). ... 

Maruoka also utilized 3,3 -modified binaphthyl-derived chiral primary amine 21, in combination with trifluoromethanesulfonic acid (TfOH), as a catalyst for the Diels-Alder reaction of a-substituted a,(i-unsaturated aldehydes with cyclopenta-diene, which afforded the corresponding cycloadducts possessing an all-carbon quaternary stereocenter with good to high stereoselectivity (Scheme 7.34) [58]. 

RS Oakes, TJ HeppenstaU, N Shezad, AA Clifford, CM Rayner. Use of scandium tris(trifluoromethanesulfonate) as a Lewis acid catalyst in supercritical carbon dioxide efficient Diels-Alder reactions and pressure dependent enhancement of endo exo stereoselectivity. Chem Commun 1459-1460, 1999. 

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