Chiral vicinal diamines including 2-aminomethyl indolines and pyrrolidines are useful as

Chiral vicinal diamines including 2-aminomethyl indolines and pyrrolidines are useful as ligands for catalytic asymmetric reactions and are also found as important components of bioactive compounds. 2-aminomethyl indolines and pyrrolidines Aurantio-obtusin are used as ligands for catalytic asymmetric reactions1-4 and are also found as important components of bioactive compounds.5-7 Development of reactions that allow direct access to chiral vicinal diamines from readily available alkenes has been a longstanding interest and challenge in organic synthesis. Recent advances in alkene diamination technology8-14 have yielded a number of promising strategies yet catalytic enantioselective alkene diaminations remain rare. Since 2007 Shi and co-workers have developed elegant intermolecular Pd- and Cu-catalyzed enantioselective diene diamination reactions using diaziridinone reagents that serve as both the diamine source and oxidant (Scheme 1).15-18 Additionally Muniz and co-workers reported the use of a hypervalant chiral iodine(III) reagent for intermolecular diamination Aurantio-obtusin of styrenes in 2011.19 20 In 2010 2010 we reported four examples of copper-catalyzed intra/intermolecular alkene diaminations and one promising albeit unoptimized example of a catalytic enantioselective diamination reaction that resulted in the synthesis of a chiral 2-aminomethyl indoline in 71% ee using the readily available (R R)-Ph-box ligand (Scheme 1).21 Michael and co-workers reported a Pd-catalyzed enantioselective diamination that provides substituted chiral 2-aminomethylpyrrolidines in very good to excellent enantioselectivities and in moderate to good yields in 2013.22 Several γ-unsaturated amides and carbamates undergo this [Pd(R)-Ph-quinox](TFA)2-catalyzed reaction where (SO2Ph)2NF (NFBS) is used as both the oxidant and amine source (Scheme 1). These enantioselective alkene diamination reactions are largely complementary where each fits best with specific substrate and product classes. Scheme 1 Enantioselective Alkene Diamination Herein we report a significant expansion of the scope of our copper-catalyzed inter/intramolecular alkene diamination protocol for the synthesis of substituted indolines and pyrrolidines. Importantly we have optimized and expanded the enantioselective reaction to where we average between 81-91% ee for 2-aminomethyl indolines and 89 to >95% ee for 2-amino pyrrolidines (vide infra). A major new enabling advance in our enantioselective diamination reaction protocol was realized by employing KMnO4 as an oxidation catalyst (vide infra). Aurantio-obtusin This enantioselective diamination reaction is distinct from the other protocols in that the amine component is not pre-oxidized allowing for a generally broader scope of readily available amine sources to be employed. Results and Discussion The scope in the racemic copper-catalyzed alkene diamination21 for the formation of 2-aminomethyl indolines CTMP was expanded as summarized in Table 1. Most of these reactions were run using 20 mol % of copper(2-ethylhexanoate)2 300 mol % of MnO2 2.2 equiv of external amine nucleophile and 1 equiv of 2 6 pyridine as base in α α α-trifluorotoluene at 110 °C for 24 h. Other oxidants [e.g. O2 (1 atm) (t-BuO)2] were also examined for the purpose of copper catalyst turnover [believed to be Cu(I) to Cu(II) vide infra]. While O2 was a poor oxidant for this reaction (not shown) (t-BuO)2 proved to be an effective oxidant though still not as effective as MnO2 (Table 1 entry 1 compare conditions a and b). Table 1 Scope of the catalytic diamination of 2-allylanilinesa 2 with both alkyl and aryl sulfonamide groups undergo efficient diamination under the optimized reaction conditions (a). External amine nucleophiles including TsNH2 MsNH2 2 (SESNH2) and benzamide were effective although benzamide provided a comparatively lower yield (Table 1 entries 1-4).21 N-Tosyl-2-allyl aniline 1b provided 64% of diamine Aurantio-obtusin 2e under these catalytic conditions where an additional 31% of the material was sultam 3 (vide infra Scheme 2). Use of the hindered 3 5 sulfonamide 1e provided increased diamination yields compared to 1b (68-80% yield Table 1 entries 8-14) and no sultam products 3 likely due to greater steric blocking of the ortho sites on the sulfonamide’s arene (vide.