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[Structure: see text] The asymmetric transfer hydrogenation of fluoroalkyl ketones mediated by [Ru(eta6-arene)((S,S)-R2NSO2DPEN)] catalysts using HCO2H-Et3N afforded the corresponding alcohols with high ee's and in excellent yields.

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A highly efficient enantio- and diastereoselective catalyzed asymmetric transfer hydrogenation via dynamic kinetic resolution (DKR–ATH) of α,β-dehydro-α-acetamido and α-acetamido benzocyclic ketones to ent-trans-β-amido alcohols is disclosed employing a new ansa-Ru(II) complex of an enantiomerically pure syn-N,N-ligand, i.e. ent-syn-ULTAM-(CH2)3Ph. DFT calculations of the transition state structures revealed an atypical two-pronged substrate attractive stabilization engaging the commonly encountered CH/π electrostatic interaction and a new additional O=S=O···HNAc H-bond hence favoring the trans-configured products.

New 3 rd generation designer ansa-ruthenium(II)c omplexes featuring N,C-alkylene-tethered N,N-dialkylsulfamoyl-DPEN/h 6 -arene ligands,e xhibited good catalytic performance in the asymmetric transfer hydrogenation (ATH) of various classes of (het)arylk etones in formic acid/triethylamine mixture.I np articular, benzo-fused cyclic ketones furnished 98 to > 99.9% ee using al ow catalyst loading.Keywords: alcohols;a symmetric catalysis;Nl igands;reduction;ruthenium In asymmetric transfer hydrogenation (ATH)o fa ryl ketones using HCO 2 H/Et 3 Nm ixture, ansa-ruthenium(II)-type complexes with intra-covalently tethered diaminea nd h 6 -arene ligand units (complexes A-D of Figure 1) have displayed improved turnover rates over the untethered version. [1,2] In fact, 2 nd and 3 rd generation designed complexes wherein the h 6 -arene ligand is linked to either SO 2 DPEN terminal( available in both enantiomericf orms, DPEN = trans-1,2-diphenylethylenediamine) demonstratede nhancedl ongevity of the catalytic species.T his aspect is economically attractivep romoting theiri ndustrial implementation for the synthesis of enantioenriched a-substituted arylmethanols. [3] We have recentlyi ntroduced a2 nd generation-type {RuCl[(S,S)-DPEN-SO 2 N(Me)(CH 2 ) n (h 6 -aryl)]}c omplex series (complex B)[4] wherein a para-substituted h 6 -phenyl (e.g., p-Tol, p-i-Pr-C 6 H 4 )t ethered to DPEN with -SO 2 N(Me)(CH 2 ) n -( n= 2o r3 )e xhibited an exceptionally high efficiency in the ATHo fa ryl ketones.[2i,k] Thus,u sing substrate-to-catalystr atios (S/Cs) of 200 to 1000, 1-naphthylk etones, a-tetralone, achloroacetophenone,a nd 1,3-diaryl b-diketones furnished at 40-60 8 8Ci nr easonable times the corresponding alcohols in > 98% to virtually perfect ees with full conversion. Given the higher activity of the known 3 rd generation ansa-Ru(II) complexes versus the 2 nd generation,w ew ere interested to explore this option using our R 2 NSO 2 DPEN [5] ligand. Herein, we present an ansa-Ru(II) complex series 1 in which the h 6 -arene is alkylene-tethered to R 2 NSO 2 DPEN from the N'-terminal( a" transshifted tether" comparedt ot he 2 nd generation version) (Scheme 1), andt heir ATHr esults against various types of prostereogenic aryl ketones.Then ew homochiral (S,S)-R 2 NSO 2 DPEN-(CH 2 ) n (h 6 -p-aryl)-type combined preligands 3,w herein the "(CH 2 ) n " ansa-bridge length and the anchored "h 6 -aryl" para end-substituent have been systematically varied, were preparedb yu sf ollowing an improved

A highly diastereo- and enantioselective Ru(II)-catalyzed dynamic kinetic resolution-asymmetric transfer hydrogenation (DKR-ATH) of α-(N-sulfonylimino) and α-(N-sulfonylamino) aryl ketones to 4-hydroxy-benzo-δ- and 3-(α-hydroxy-arylmethyl)-benzo-γ-sultams is presented. By employing enantiopure ansa-Ru[PipSODPEN(CH)Ph] cat. II with S/C = 10 000 in a HCOH/EtN binary mix, up to >99.9% ee and dr >99:1 are obtained with 100% conversion under mild conditions. Application to access the stereopure "structurally simplified TsDPEN" N,N-ligand syn-3-(α-aminobenzyl)-benzo-γ-sultam ("syn-ULTAM") and its structural isomer trans-4-amino-3-phenyl-benzo-δ-sultam (trans-4) is demonstrated.