Gold‐Catalyzed Oxidative Cyclizations on 1,4‐Enynes: Evidence for a γ‐Substituent Effect on Wagner–Meerwein Rearrangements

Gold‐Catalyzed Iminations of Terminal Propargyl Alcohols with Anthranils with Atypical Chemoselectivity for C(1)‐Additions and 1,2‐Carbon Migration

“…We first prepared tertiarya lcohols 1b-1d bearing two different alkyl groups (R 1 = Me, R 2 = Et, n-propyl,a nd n-pentyl);r esulting products 3b-3d arose from a1 ,2-migration of small methyl, in accordw ith the Wagner-Meerwein reaction. [10] For secondary propargyl alcohols 1e-1i (R 1 = 4XC 6 H 4 ,R 2 = H, Me, Cl, tBu, and OMe), their alkyne iminations afforded the corresponding products 3e-3i in satisfactory yields;a1,2-phenyl migration occurred preferably whereas a1 ,2-hydrogen shift was entirely absent.W hen product 3e was treated with p-TSA (p-toluenesulfonica cid, 10 mol %) in hot DCE (70 8C, 12 h), the E/Z ratio remained the same (E/Z = 6:1);t his observation suggests that the E-isomer was produced thermodynamically favorably.F or two secondary alcohols, 1j (R 1 = cyclopropyl) and 1k (R 1 = CH= [a] 1a (0.10 m,1 .0 equiv) and 2a (2.5 equiv). [ b] Product yields wereo btained after purification from as ilica column.…”

“…With variations of the silver salts as in P(tBu) 2 (obiphenyl)AuCl/AgX 2 (X = SbF 6 and OTf), the yields of compound 3a were 10 %a nd 21 %, respectively (entries6-7). For P(tBu) 2 (o-biphenyl)AuCl/AgNTf 2 ,i nv ariouss olvents, the yields were 35 %i nb enzene, 38 %i nT HF,5 2% in toluene, and entirely inactive in DMSO (entries [8][9][10][11].…”

“…For representative products 3a and 3e,t he presence of Et 3 N/DMAP( 4-dimethylaminopyridine) enabled their intramolecular cyclizationst oa fford quinoline derivatives 8a and 8b in 90-92 %y ields, together with al oss of RCO 2 H[ Scheme2 (9)]. [12] With this functionalization, [13] we were able to develop ar elay catalysis involving an initial gold-catalyzed C(1)-imination of 3,3-dimethylprop-1-yn-3-ol 1a with an anthranil 2a to allow a complete formation of a-amino-2-en-1-one 3a,f ollowed by a Et 3 N/DMAP-catalyzed [12] intramolecularc yclization;t he resulting quinoline 8a was obtained in 72 %y ield in this one-pot sequence[Scheme 2 (10)].…”

“…[6d, 8] A1 ,2-hydrogen migration, as depicted by ln-6,i sa ne xclusive route for gold carbenes, including those bearing a-hydroxyl and -amino groups [6d, 8f] in accord with the Wagner-Meerweinr earrangement. [10]…”

Gold‐Catalyzed 1,2‐Oxoarylations of Nitriles with Pyridine‐Derived Oxides

“…[1][2][3][4][5] These oxidations lead to 1,2-oxofunctionalization products by two paths. [1][2][3][4][5] These oxidations lead to 1,2-oxofunctionalization products by two paths.…”