Nickel-catalyzed heterocycle construction with stereoselective exocyclic alkene introduction

Diastereomeric Atropisomers from a Chiral Diyne by Cobalt(I)‐Catalyzed Cyclotrimerization

“…All liquid reagents were distilled under argon prior to use. [32] (S)-Proline [(S)-3, 10.0 g, 86.9 mmol] was suspended in dry methanol (100 mL) under argon and cooled to 0°C, afterwards SOCl 2 (7.0 mL, 95.6 mmol) was added dropwise. Chromatographic purifications were done with 240-400 mesh silica gel or an automated flash chromatography system (Biotage SP1).…”

“…The liquid starting materials were dried with and distilled from molecular sieves under argon before use. After evaporation of the solvent, the oily residue was purified by column chromatography on silica gel with n-hexane/ethyl acetate, 4:1 (v/v + 1 % Et 3 N) as the eluent and compound (S)-9 was obtained as colorless oil [32] Lithium aluminum hydride (100 mL, 100 mmol, 1 m in Et 2 O) was diluted with dry Et 2 O (200 mL) in a 500 mL flask fitted with a dropping funnel and argon inlet. THF used as eluent for chromatographic separations was distilled before use to remove the added stabilizer (BHT) or unstabilized THF was used.…”

“…All other compounds and reagents not referenced were commercially available and have been purchased. [32] (S)-Proline [(S)-3, 10.0 g, 86.9 mmol] was suspended in dry methanol (100 mL) under argon and cooled to 0°C, afterwards SOCl 2 (7.0 mL, 95.6 mmol) was added dropwise. The reaction mixture was heated for 1 h under reflux and allowed to cool to room temp.…”

“…for C 9 H 14 NO 2 [M + H] + 168.1019; found 168.1020. (S)-[1-(Prop-2-ynyl)pyrrolidin-2-yl]methanol [(S)-10]:[32] Lithium aluminum hydride (100 mL, 100 mmol, 1 m in Et 2 O) was diluted with dry Et 2 O (200 mL) in a 500 mL flask fitted with a dropping funnel and argon inlet. The ester (S)-9 (8.3 g, 50 mmol) was added dropwise over about 2.5 h and the reaction mixture was stirred for additional 4 h. TLC control [eluent: n-hexane/ethyl acetate, 1:1 (v/v) + 1 % Et 3 N] indicated complete conversion and the reaction was quenched with a mixture of NH 4 Cl/aq.…”

Synthesis of heteroatom-containing pyrrolidine derivatives based on Ti(O-iPr)4 and EtMgBr-catalyzed carbocyclization of allylpropargyl amines with Et2Zn

“…20 A known method for the preparation of acyl-substituted pyrrolidines is Me 2 Zn/Ni(0)promoted cyclization of nitrogen-containing alkynyl enones. 21 The cyclization of N-allyl-N-benzyl-3-(trimethylsilyl)-2-propynylamine on treatment with triallylmanganate is not stereoselective and gives a 1 : 1 mixture of Z/E isomers in 55% overall yield. 22 Meanwhile, the reaction of N-benzyl-N- (3-(trimethylsilyl)prop-2yn-1-yl)prop-2-en-1-amine with four equivalents of methallylmagnesium chloride in the presence of catalytic amounts of CrCl 3 is stereoselective, giving the E-isomer in 73% yield.…”