6672-24-8

Upstream product

• 917-64-6 methyl magnesium iodide 
• 79681-26-8 2-[(S)-(4-methylphenyl)sulfinyl]cyclopent-2-en-1-one 
• 930-30-3 cyclopent-2-enone 
• 917-54-4 methyllithium 
• 2758-18-1 3-Methyl-2-cyclopenten-1-one 
• 544-97-8 dimethyl zinc(II) 
• 1757-42-2 3-methyl-cyclopentanone 
• 2999-74-8 dimethylmagnesium 
• 3973-43-1 4-methylpent-4-enal 

Downstream Products

• 87921-02-6 (+)-2,5-dibenzylidene-3-methylcyclopentanone 
• 74965-63-2 (S)-(-)-3-methylcyclopentanone 2,4-dinitrophenylhydrazone 
• 930-59-6 (1R,3R)-3-methylcyclopentanol 
• 68680-80-8 (-)(1R)-1r-methyl-cyclopentanol-(3c) 
• 65354-34-9 (1R)-cis-3-Methyl-cyclopentanol 
• 68680-81-9 (1S)-trans-3-Methyl-cyclopentanol 

Relevant academic research and scientific papers

A robust and stereocomplementary panel of ene-reductase variants for gram-scale asymmetric hydrogenation

We report an engineered panel of ene-reductases (ERs) from Thermus scotoductus SA-01 (TsER) that combines control over facial selectivity in the reduction of electron deficient C[dbnd]C double bonds with thermostability (up to 70 °C), organic solvent tolerance (up to 40 % v/v) and a broad substrate scope (23 compounds, three new to literature). Substrate acceptance and facial selectivity of 3-methylcyclohexenone was rationalized by crystallisation of TsER C25D/I67T and in silico docking. The TsER variant panel shows excellent enantiomeric excess (ee) and yields during bi-phasic preparative scale synthesis, with isolated yield of up to 93 % for 2R,5S-dihydrocarvone (3.6 g). Turnover frequencies (TOF) of approximately 40 000 h?1 were achieved, which are comparable to rates in hetero- and homogeneous metal catalysed hydrogenations. Preliminary batch reactions also demonstrated the reusability of the reaction system by consecutively removing the organic phase (n-pentane) for product removal and replacing with fresh substrate. Four consecutive batches yielded ca. 27 g L?1 R-levodione from a 45 mL aqueous reaction, containing less than 17 mg (10 μM) enzyme and the reaction only stopping because of acidification. The TsER variant panel provides a robust, highly active and stereocomplementary base for further exploitation as a tool in preparative organic synthesis.

Counterion Enhanced Organocatalysis: A Novel Approach for the Asymmetric Transfer Hydrogenation of Enones

We present a novel strategy for organocatalytic transfer hydrogenations relying on an ion-paired catalyst of natural l-amino acids as main source of chirality in combination with racemic, atropisomeric phosphoric acids as counteranion. The combination of a chiral cation with a structurally flexible anion resulted in a novel chiral framework for asymmetric transfer hydrogenations with enhanced selectivity through synergistic effects. The optimized catalytic system, in combination with a Hantzsch ester as hydrogen source for biomimetic transfer hydrogenation, enabled high enantioselectivity and excellent yields for a series of α,β-unsaturated cyclohexenones under mild conditions. Moreover, owing to the use of readily available and chiral pool-derived building blocks, it could be prepared in a straightforward and significantly cheaper way compared to the current state of the art.

Imido-P(v) trianion supported enantiopure neutral tetrahedral Pd(II) cages

Charge-neutral chiral hosts are attractive due to their ability to recognize a wide range of guest functionalities and support enantioselective processes. However, reports on such charge-neutral cages are very scarce in the literature. Here, we report an enantiomeric pair of tetrahedral Pd(ii) cages built from chiral tris(imido)phosphate trianions and oxalate linkers, which exhibit enantioselective separation capabilities for epichlorohydrin, β-butyrolactone, and 3-methyl- and 3-ethyl cyclopentanone.

Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones followed by trapping with allyl iodide derivatives

Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones proceeded in the presence of 0.1 mol% of Cu(OTf)2 and 0.25 mol% of an N,N,P-ligand containing a quinoline moiety to afford the corresponding conjugated adducts in 99%ee. The intermediate zinc enolates were trapped with substituted allyl iodides to give disubstituted ketones with high diastereoselectivity and enantioselectivity.

Copper-catalyzed asymmetric 1,4-conjugate addition of dialkylzinc to enones

Asymmetric 1,4-conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)-6,6'-Br2-BINOL(1f), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy2NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to84%ee) and isolated yield (up to 94%) under mild reaction conditions.

Directed evolution of an enantioselective enoate-reductase: Testing the utility of iterative saturation mutagenesis

Directed evolution utilizing iterative saturation mutagenesis (ISM) has been applied to the old yellow enzyme homologue YqjM in the quest to broaden its substrate scope, while controlling the enantioselectivity in the bioreduction of a set of substituted cyclopentenone and cyclohexenone derivatives. Guided by the known crystal structure of YqjM, 20 residues were selected as sites for saturation mutagenesis, a pooling strategy based on the method of Phizicky [M. R. Martzen, S. M. McCraith, S. L. Spinelli, F. M. Torres, S. Fields, E. J. Grayhack, E. M. Phizicky, Science 1999, 286, 1153-1155] being used in the GC screening process. The genes of some of the hits were subsequently employed as templates for randomization experiments at the other putative hot spots. Both (R)-and (S)-selective variants were evolved using 3-methylcyclohexenone as the model substrate in the asymmetric bioreduction of the olefinic functionality, only small mutant libraries and thus minimal screening effort being necessary. Some of the best mutants also proved to be excellent catalysts when testing other prochiral substrates without resorting to additional mutagenesis/screening experiments. Thus, the results constitute an important step forward in generalizing the utility of ISM as an efficient method in laboratory evolution of enzymes as catalysts in organic chemistry.

Asymmetric bioreduction of C=C bonds using enoate reductases OPR1, OPR3 and YqjM: Enzyme-based stereocontrol

Three cloned enoate reductases from the "old yellow enzyme" family of flavoproteins were investigated in the asymmetric bioreduction of activated alkenes. 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from Lycopersicon esculentum (tomato), and YqjM from Bacillus subtilis displayed a remarkably broad substrate spectrum by reducing α,β-unsaturated aldehydes, ketones, maleimides and nitroalkenes. The reaction proceeded with absolute chemoselectivity-only the conjugated C=C bond was reduced, while isolated olefins and carbonyl groups remained intact-with excellent stereoselectivities (ees up to >99%). Upon reduction of a nitroalkene, the stereochemical outcome could be determined via choice of the appropriate enzyme (OPR1 versus OPR3 or YqjM), which furnished the corresponding enantiomeric nitroalkanes in excellent ee. Molecular modelling suggests that this "enzyme-based stereocontrol" is caused by subtle differences within the active site geometries.

Enantioselective hydrogenation of enones with a hydroformylation catalyst

Use of a typical rhodium precatalyst for hydroformylation results in the enantioselective hydrogenation of cyclic enones with up to 90% ee. Extensive screening of chiral ligands reveals the simple ligand Chiraphos as the best ligand, so far. The hydrogenation shows high chemoselectivity. Exclusive formation of saturated, chiral b-branched ketones is observed. It is proposed that the catalyst follows a frustrated hydroformylation pathway ("monohydride-based mechanism") and differs by that from the classical cationic Schrock-Osborn type rhodium precatalysts ("dihydride-based mechanism") for enantioselective hydrogenation. The catalyst operates under neat conditions and is easily recyclable by simply distilling off the reaction mixture and treatment with syn gas prior to hydrogenation.

Organocatalytic transfer hydrogenation of cyclic enones

The first enantioselective organocatalytic transfer hydrogenation of cyclic enones has been accomplished. The use of iminium catalysis has provided a new organocatalytic strategy for the enantioselective reduction of β,β-substituted α,β-unsaturated cycloalkenones, to generate β-stereogenic cyclic ketones. The use of imidazolidinone 4 as the asymmetric catalyst has been found to mediate the hydrogenation of a large class of enone substrates with tert-butyl Hantzsch ester serving as an inexpensive source of hydrogen. The capacity of catalyst 4 to enable enantioselective transfer hydrogenation of cycloalkenones has been extended to five-, six-, and seven-membered ring systems. The sense of asymmetric induction is in complete accord with the stereochemical model first reported in conjunction with the use of catalyst 4 for enantioselective ketone Diels-Alder reactions. Copyright

Hydride reduction of alpha, beta-unsaturated carbonyl compounds using chiral organic catalysts

Nonmetallic, chiral organic catalysts are used to catalyze the 1,4-hydride reduction of an α,β-unsaturated carbonyl compound. The α,β-unsaturated carbonyl compound may be an aldehyde or cyclic ketone, and the hydride donor may be a dihydropyridine. The reaction is enantioselective, and proceeds with a variety of hydride donors, catalysts, and substrates. The invention also provides compositions effective in carrying out the 1,4-hydride addition of α,β-unsaturated carbonyl compounds.