Ru-Catalyzed Stereoselective Addition of Imides to Alkynes

Abstract

A catalyst system formed in situ from bis(2-methylallyl)cycloocta-1,5-dieneruthenium(II) ((cod)Ru[met]2), a phosphine, and scandium(III) trifluoromethanesulfonate (Sc(OTf)3) was found to efficiently catalyze the anti-Markovnikov addition of imides to terminal alkynes, allowing mild and atom-economic synthesis of enimides. Depending on the phosphine employed, both the (E)- and the (Z)-isomer can be accessed stereoselectively.

Oligosubstituted Pyrroles Directly from Substituted Methyl Isocyanides and Acetylenes

“…The prepared derivatives can also be easily transformed into pyrroles of higher or lower order of substitution according to established protocols. [30,31] Experimental Section Starting materials: Methyl cyclopropylpropiolate (2 a), [32] tert-butyl cyclopropylpropiolate (2 b), [33] 4-nitrophenylmethyl isocyanide (1 g), [34] cyanomethyl isocyanide (1 d), [35] diethyl (3-methoxyprop-1-ynyl)phosphonate (2 d), [36] ethyl trifluoromethylpropiolate (2 e), [37] methyl morpholin-4-ylpropiolate (2 f), [38] methyl 3-(4-fluorophenyl)propiolate (2 i), [39] methyl 3-(4-trifluoromethylphenyl)propiolate (2 j), [40] methyl 3-(thiophen-2-yl)propiolate (2 l), [41] methyl 3-(pyridin-2-yl)propiolate (2 k), [42] methyl (1-methoxycarbonylethynylcyclopropyl)propiolate (2 m), [43] cyclopropylacetylene (2 v), [44] CpCuPA C H T U N G T R E N N U N G (OMe) 3 , [19] 1-deuterohex-1-yne ([D]2 r) [45] were prepared according to literature procedures. Commercial nanosize-copper powder (Aldrich) was preactivated by heating in vacuo (0.05 mbar) at 150 8C overnight, and it was then stored under Ar.…”

Regioselective Heck Reaction of N‐Vinylphthalimide: A General Strategy for the Synthesis of (E)‐N‐Styrylphthalimides and Phenethylamines

“…These results are probably due to partial decomposition of the resin working at this rather high temperature. When the reaction was performed in toluene at reflux, a lower Pd leaching was detected, but competitive homocoupling of 4-bromoacetophenone to give 4,4'diacetylbiphenyl was observed (Table 3, entries [4][5][6].…”

“…[2d] Although N-vinylphthalimide is commercially available, the main drawback found for this Heck acceptor is the control of the a-and b-regioselectivity, [2,3] which is due to the competition of cationic and neutral mechanisms, respectively, in electron-rich alkenes. [4] In addition, barylated N-vinylphthalimides are important compounds, [5] for instance, the metabolic drug I is a b2 adrenoceptor agonist, [6] compound II is a fungicide, [7] and III is a non-linear, optically active material [8] ( Figure 2). We have recently studied the Heck reaction [9] of electron-rich alkenes using Cy 2 NMe as base and 2 or palladacycles 3, 4, or 5 [10] (Figure 3) as catalysts under phosphine-free conditions.…”

Addition Reactions: Polar Addition

“…Depending on the phosphine employed, E-and Z-isomers can be accessed stereoselectively. 96 The presence of catalytic amounts of halide salts (e.g. Bu 4 NI) was found to enhance dramatically the efficiency of hydroesterification of alkenes (e.g.…”