cas 4276-09-9, (R)-(-)-2-Amino-3-methyl-1-butanol

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A Spiroalkylation Method for the Stereoselective Construction of α-Quaternary Carbons and Its Application to the Total Synthesis of (R)-Puraquinonic Acid
Cyclic α-quaternary carbon stereocenters were prepared from biselectrophillic substrates and an easily prepared chiral bicyclic sulfonyl lactam. This was achieved in two steps by spiroalkylation, employing biphasic reaction conditions with a phase-transfer catalyst, followed by reduction and alkylation with a series of alkyl halide electrophiles. The products of this method were isolated in good yields with with high levels of diastereoselectivity. This methodology was employed in the enantioselective total synthesis of (R)-puraquinonic acid (1) for a late-stage installation of the α-quaternary carbon stereocenter. This enabled the shortest synthesis of 1 to date, an eight-pot sequence providing an overall yield of 14%.
Elmehriki, Adam A. H.,Gleason, James L.
supporting information
p. 9729 - 9733
(2019/12/02)

Total Enantioselective Synthesis of the Endophytic Fungal Polyketide Phomolide H and Its Structural Revision
A total synthesis of the proposed structure of the natural polyketide-macrolactone phomolide H 2 has been achieved following a bidirectional strategy from l-tartaric acid. The originally assigned structure of phomolide H displayed discordant NMR spectroscopic data in comparison with synthetic 2. The synthetic strategy was extended to prepare diastereomers and epimeric methyl-ethers of the natural product, structural analysis of which revealed a match of the natural product with diastereomer 27. The structural revision of phomolide H from 2 to the methanol solvate of compound 27 is presented.
McNulty, James,McLeod, David
supporting information
p. 29 - 33
(2017/01/14)

Heterogeneous Catalytic Hydrogenation of Chiral Amino Acid Methyl Esters to Amino Alcohols with Retention of Configuration Over Mg-Modified Cu/ZnO/Al2O3 Catalyst
Selective hydrogenation of amino acid methyl esters to chiral amino alcohols is an important and fascinating process. The CuZn0.3Mg0.1AlOx catalyst for the synthesis of chiral amino alcohols was prepared by the fractional
Zhan, Bing,Zhang, Shuangshuang,Yu, Jun,Xiao, Xiuzheng,Guo, Xiaoming,Mao, Dongsen,Lu, Guanzhong
p. 2160 - 2166
(2017/07/25)

Enantioselective Total Synthesis of the Proposed Structure of the Endophytic Fungal Metabolite Phomolide G: Structural Revision and Unambiguous Stereochemical Assignment
A total synthesis of the proposed structure of the natural macrolactone phomolide G (1) by a bidirectional strategy from L-tartaric acid is reported. The ω-terminus of the molecule was elaborated by nitrile extension, C3-alkylation and a substrate-controlled 1,3-ketone reduction. The α-terminus was extended by a C2aldehyde-to-alkenal homologation followed by an auxiliary controlled aldol reaction. Macrolactonization and deprotection yielded compound 1 (confirmed by X-ray analysis). This putative structure of phomolide G displayed discordant NMR spectroscopic data in comparison with those of the natural product. Detailed inspection of all NMR spectroscopic data available indicated phomolide G to be likely a diastereomer of 1. The synthetic strategy developed allows control of the absolute stereochemistry at all four chiral secondary alcohol groups. Further manipulation allowed for the preparation of diastereomer 33, the1H and13C NMR spectroscopic data of which are in full accord with that reported for the natural product.
McNulty, James,McLeod, David,Jenkins, Hilary A.
supporting information
p. 688 - 692
(2017/01/18)

Design, Synthesis, Fungicidal Activity, and Unexpected Docking Model of the First Chiral Boscalid Analogues Containing Oxazolines
Chirality greatly influences the biological and pharmacological properties of a pesticide and will contribute to unnecessary environmental loading and undesired ecological impact. No structure and activity relationship (SAR) of enantiopure succinate dehydrogenase inhibitors (SDHIs) was documented during the structure optimization of boscalids. On the basis of commercial SDHIs, oxazoline natural products, and versatile oxazoline ligands in organic synthesis, the first effort was devoted to explore the chiral SDHIs and the preliminary mechanism thereof. Fine-tuning furnished chiral nicotinamides 4ag as a more promising fungicidal candidate against Rhizoctonia solani, Botrytis cinerea, and Sclerotinia sclerotiorum, with EC50 values of 0.58, 0.42, and 2.10 mg/L, respectively. In vivo bioassay and molecular docking were investigated to explore the potential in practical application and plausible novelty in action mechanism, respectively. The unexpected molecular docking model showed the different chiral effects on the binding site with the amino acid residues. This chiral nicotinamide also featured easy synthesis and cost-efficacy. It will provide a powerful complement to the commercial SDHI fungicides with the introduction of chirality.
Li, Shengkun,Li, Dangdang,Xiao, Taifeng,Zhang, Shasha,Song, Zehua,Ma, Hongyu
p. 8927 - 8934
(2016/12/07)

Direct Generation of Triketide Stereopolyads via Merged Redox-Construction Events: Total Synthesis of (+)-Zincophorin Methyl Ester
(+)-Zincophorin methyl ester is prepared in 13 steps (longest linear sequence). A bidirectional redox-triggered double anti-crotylation of 2-methyl-1,3-propane diol directly assembles the triketide stereopolyad spanning C4-C12, significantly enhancing step economy and enabling construction of (+)-zincophorin methyl ester in nearly half the steps previously required.
Kasun, Zachary A.,Gao, Xin,Lipinski, Radoslaw M.,Krische, Michael J.
p. 8900 - 8903
(2015/08/03)

Readily available ferrocenyl-phosphinite ligands for Ru(II)-catalyzed enantioselective transfer hydrogenation of ketones and fabrication of hybrid heterojunctions
A variety of phosphinite based on ferrocenyl moiety possessing central chirality have been screened as ligands for ruthenium(II)-catalyzed transfer hydrogenation of acetophenone derivatives using iso-PrOH as the hydrogen source to afford the corresponding product, (R) or (S)-1-phenylethanol derivatives with high conversions and good enantioselectivities. These complexes were also employed in the asymmetric reduction of different prochiral ketones (up to 85% ee). A comparison of the catalytic properties of amino alcohols and other analogs based on ferrocenyl backbone is also discussed briefly. The structures of these ligands and their corresponding complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis. Furthermore, organic-inorganic hybrid heterojunctions were also fabricated by forming thin films of ruthenium(II) complexes on n-Si and evaporation of Au as front contact. Current-voltage (I-V) characteristics of the structures showed excellent rectification properties. Electrical parameters including ideality factor, barrier height and series resistance were determined using I-V and capacitance-voltage (C-V) data. Finally, photoelectrical properties of the structures were examined by means of a solar simulator with AM1.5 global filter.
Ak, Bünyamin,Aydemir, Murat,Ocak, Yusuf Selim,Durap, Feyyaz,Kayan, Cezmi,Baysal, Akin,Temel, Hamdi
p. 244 - 253
(2013/12/04)

Highly enantioselective Michael addition of diethyl malonate to chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors
Chalcones are still challenge substrates in Michael reactions, and only limited success has been achieved. This work describes a highly enantioselective Michael addition of diethyl malonate with chalcones catalyzed by cinchona alkaloids-derivatived bifunctional tertiary amine-thioureas bearing multiple hydrogen-bonding donors.
Liu, Yulong,Wang, Xie,Wang, Xiaoyun,He, Wei
supporting information
p. 3163 - 3166
(2014/05/06)

Synthesis of salicylic acid-based 1,3,4-oxadiazole derivatives coupled with chiral oxazolidinones: Novel hybrid heterocycles as antitumor agents
A series of novel salicylic acid-based 1,3,4-oxadiazoles derivatives coupled with chiral oxazolidinones were synthesized to screen for their in vitro antitumor activity against five human cancer cell lines. Some of these compounds showed good antitumor activities with IC50values ranging from 31.19-57.21 μM. Among the tested compounds 11, 15, 19,23,24, and 34 showed broad-spectrum antitumor activity against all the cell lines. In particular, compound 19 revealed remarkable antitumor activity with IC50 = 31.19-41.87 μM. A431 was the most sensitive cell line against all the compounds studied, followed by HeLa, MCF-7, A549 and HepG2. Structures of newly synthesized compounds were confirmed by IR,1 H NMR, 13C NMR and HRMS spectral data
Murty,Penthala, Raju,Nath, Lekshmi R.,Anto, Ruby John
p. 1133 - 1142
(2015/03/31)

Tunable ferrocenyl-phosphinite ligands for the ruthenium(II)-catalyzed asymmetric transfer hydrogenation of ketones
We report here new examples of enantiomerically pure monodendate phosphinite ligands containing both a ferrocene moiety and NH bridging moiety adjacent to the stereocenter, as well as their ruthenium(II) dichloro complexes. The phosphinites based on ferrocenyl moiety possessing stereogenic center have been screened as ligands for ruthenium(II)-catalyzed transfer hydrogenation of aromatic ketones to give corresponding secondary alcohols using iso-PrOH as the hydrogen source in the presence of NaOH. Up to 99% conversion with 97% ee was obtained in the transfer hydrogenation of acetophenone derivatives. Furthermore, the catalytic properties of these catalysts based on ferrocenyl-phosphinite backbone are also discussed briefly. The structures of these ligand and their corresponding complexes have been elucidated by a combination of multinuclear NMR spectroscopy, IR spectroscopy and elemental analysis.
I?ik, U?ur,Aydemir, Murat,Meri?, Nermin,Durap, Feyyaz,Kayan, Cezmi,Temel, Hamdi,Baysal, Akin
p. 225 - 233
(2013/10/08)

Modular bifunctional chiral thioureas as versatile organocatalysts for highly enantioselective aza-Henry reaction and michael addition
A series of new modular bifunctional chiral thiourea organocatalysts were synthesized from natural Cinchona alkaloids and amino acids, and their performance in the aza-Henry reaction of nitroalkanes to imines, the Michael addition of acetylacetone to nitroolefins and the Michael addition of acetone to nitroolefins was investigated. Under the mild conditions, the important building blocks β-nitro amines and γ-nitro carbonyl compounds could be obtained in good yields (up to 95%) with excellent enantioselectivities (up to 99% ee) and diastereoselectivity (up to 17:1). Copyright
Li, Hua,Zhang, Xu,Shi, Xin,Ji, Nan,He, Wei,Zhang, Shengyong,Zhang, Bangle
p. 2264 - 2274
(2012/11/06)

Synthesis of imidacloprid derivatives with a chiral alkylated imidazolidine ring and evaluation of their insecticidal activity and affinity to the nicotinic acetylcholine receptor
A series of imidacloprid (IMI) derivatives with an alkylated imidazolidine ring were asymmetrically synthesized to evaluate their insecticidal activity against adult female housefly, Musca domestica, and affinity to the nicotinic acetylcholine receptor of the flies. The bulkier the alkyl group, the lower was the receptor affinity, but the derivatives methylated and ethylated at the R-5-position of the imidazolidine ring were equipotent to the unsubstituted compound. Quantitative structure-activity relationship (QSAR) analysis of the receptor affinity demonstrated that the introduction of a substituent into the imidazolidine ring was fundamentally disadvantageous, but the introduction of a substituent at the R-5-position was permissible in the case of its small size. The binding model of the synthesized derivatives with the receptor supported the QSAR analysis, indicating the existence of space for a short alkyl group around the R-5-position in the ligand-binding site. In addition, positive correlation was observed between the insecticidal activity and receptor affinity, suggesting that the receptor affinity was the primary factor in influencing the insecticidal activity even if the imidazolidine ring was modified.
Nishiwaki, Hisashi,Kuriyama, Mituhiro,Nagaoka, Hikaru,Kato, Akira,Yamauchi, Satoshi,Shuto, Yoshihiro,Akamatsu, Miki
p. 6305 - 6312,8
(2012/12/11)

Pyridine containing chiral macrocycles: Synthesis and their enantiomeric recognition for amino acid derivatives
Four novel C2-symmetric enantiomerically pure, chiral pyridine-18-crown-6 type macrocycles containing lipophilic chains at the stereogenic centers were prepared. The enantioselectivity of the new ligands toward the enantiomers of d-,l-amino acid methyl ester derivatives were also determined by 1H NMR titration method. These novel macrocycles have been showed to be strong complexing agents for d- and l-amino acid methyl ester hydrochloride salts (with Kass up to 13590 M-1 and G 0 up to 23.3 kJ mol-1 and selectivity ratio: 80:20) by 1H NMR titration methods. These macrocyclic hosts exhibited enantioselective binding towards the d-enantiomer of valine methyl ester hydrochloride with Kd/Kl up to 5.08 in CDCl3 with 0.25% CD3OD.
Deniz, Pinar,Turgut, Yilmaz,Togrul, Mahmut,Hosgoren, Halil
scheme or table
p. 6227 - 6232
(2011/09/19)

Asymmetric synthesis of β-adrenergic blockers through multistep one-pot transformations involving in situ chiral organocatalyst formation
Two birds one stone: A new atom-economical one-pot approach to enantioselective chiral drug synthesis, involving in situ multistep organocatalyst formation and the application of the reaction for multistep sequential synthesis of β-adrenergic blockers is disclosed (see scheme).
Wei, Shengwei,Messerer, Regina,Tsogoeva, Svetlana B.
supporting information; experimental part
p. 14380 - 14384
(2012/02/01)

Synthesis and evaluation of the in vitro DNA-binding properties of chiral cis-dichloro(pyridyloxazoline)platinum(II) complexes
A series of chiral cis-dichloro(pyridyloxazoline)platinum(II) and palladium(II) complexes were synthesized and their reactivity towards a defined sequence of single-stranded and double-stranded DNA was investigated in comparison to cisplatin. The compounds differed in the nature and absolute configuration of the substituent at the C4 position of the oxazoline ring. The DNA-binding ability of these compounds was evaluated by HPLC analysis, post metal exposure, of enzymatic digests of an undecamer duplex containing one putative metallation site. Polyacrylamide gel electrophoresis (PAGE) and thermal denaturation confirmed the results of the HPLC analysis, which showed that the stereochemistry and character of the substituent at the C4 position of the oxazoline ring had little effect on DNA binding, possibly due to the formation of monofunctional adducts.
Dodd, David W.,Toews, Heather E.,Trevail, Michael J.,Jennings, Michael C.,Hudson, Robert H.E.,Jones, Nathan D.
body text
p. 321 - 327
(2009/10/23)

Enantioselective syntheses of morpholines and their homologues via S N2-type ring opening of aziridines and azetidines with haloalcohols
(Chemical Equation Presented) A highly regio- and stereoselective strategy for the syntheses in high yield and enantioselectivity of a variety of substituted nonracemic morpholines and their homologues is described. The reaction proceeds via an SN2-type ring opening of activated aziridines and azetidines by suitable halogenated alcohols in the presence of Lewis acid followed by base-mediated intramolecular ring closure of the resulting haloalkoxy amine.
Ghorai, Manas K.,Shukla, Dipti,Das, Kalpataru
body text
p. 7013 - 7022
(2009/12/22)

Chiral Ti(IV) complexes of hexadentate Schiff bases as precatalysts for aldehyde allylation: unusual additive effect of trimethylsilyl chloride
Chiral dinuclear titanium(IV) complexes have been found to be more effective catalysts for the asymmetric allylation of p-nitrobenzaldehyde than their mononuclear analogues. The addition of trimethylsilyl chloride to the reaction mixture decreases the rate of the background reaction and increases the yield of the reaction catalysed by the dinuclear complex.
Belokon, Yuri N.,Chusov, Denis,Borkin, Dmitry A.,Yashkina, Lidia V.,Bolotov, Pavel,Skrupskaya, Tatiana,North, Michael
p. 459 - 466
(2008/09/19)

On the structure and chiroptical properties of (S)-4-isopropyl-oxazolidin-2-one
The specific rotation of (S)-4-isopropyl-oxazolidin-2-one is extremely solvent dependent. In chloroform it is dextrorotatory {[α]D26 = + 15.5 (c 5.2, CHCl3)}, whereas in ethanol it is levorotatory {[α]D26 = - 16.1 (c 5.2, EtOH)}.
Benoit, David,Coulbeck, Elliot,Eames, Jason,Motevalli, Majid
p. 1068 - 1077
(2008/09/20)

DABCO catalyzed reaction of various nucleophiles with activated alkynes leading to the formation of alkenoic acid esters, 1,4-dioxane, morpholine, and piperazinone derivatives
The reaction of acids, alcohols, acylamides, 1,2-diols, 1,2-diamines or amino alcohols with activated alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) was systematically investigated. A series of unsaturated alkenoic acid esters or heterocycles were formed in the reaction of monobasic or dibasic nucleophiles in excellent yields, respectively.
Fan, Ming-Jin,Li, Gao-Qiang,Liang, Yong-Min
p. 6782 - 6791
(2007/10/03)

Process for the preparation of enantiomerically enriched compounds
1. Process for the preparation of enantiomerically enriched amino aldehydes and amino alcohols, wherein a corresponding enantiomerically enriched amino nitrile is subjected to hydrogenation in the presence of hydrogen, a hydrogenation catalyst, preferably a Pd-catalyst and a mineral acid. For the preparation of an amino aldehyde hydrogen preferably is present at a hydrogen-pressure between 0.1 and 2 MPa, in particular between 0.5 and 1 MPa. The amino aldehyde preferably is isolated in the form of a chemically and configurationally stable derivative. For the preparation of an amino alcohol, preferably at least during part of the hydrogenation hydrogen is present at a hydrogen-pressure between 2 and 10 MPa, in particular between 4 and 6 MPa. In a preferred embodiment the hydrogen-pressure initially is between 0,5 and 2 MPa and subsequently, after most of the nitrile starting material is converted, the hydrogen pressure is increased to a value between 2 and 10 MPa. The enantiomerically enriched nitrile starting material may a.o. be prepared by enzymatic resolution, classical resolution, resolution via preferential crystallization, diastereomeric synthesis, catalytic asymmetric synthesis or dehydratation of amino acid amides.
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(2010/11/29)

Highly Enantioselective Synthesis of 1,2-Amino Alcohol Derivatives via Proline-Catalyzed Mannich Reaction
Here we report a new catalytic asymmetric synthesis of oxazolidin-2-ones 4 and Cbz-protected 1,2-amino alcohols 5. Our sequence is based on the chemistry of previously unknown 5-acyloxy-oxazolidin-2-ones, which are obtained via proline-catalyzed direct asymmetric three-component Mannich reaction and Baeyer-Villiger oxidation.
Pojarliev, Peter,Biller, William T.,Martin, Harry J.,List, Benjamin
p. 1903 - 1905
(2007/10/03)

Efficient procedure for the reduction of α-amino acids to enantiomerically pure α-methylamines
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Quagliato, Dominick A.,Andrae, Patrick M.,Matelan, Edward M.
p. 5037 - 5042
(2007/10/03)

2-benzyl-polycyclic guanine derivatives and process for preparing them
Antihypertensive and bronchodilating compounds of the formula or a pharmaceutically acceptable salt thereof, and a process for preparing them are disclosed, wherein: R1, R2, R3, Ra, Rb and Rc as defined in the disclosure; pharmaceutical compositions containing said compounds; methods of treatment using said compounds; and a process for preparing polycyclic guanines comprising a) reducing a nitrosopyrimidine, and treating the reduced nitrosopyrimidine with an acylating reagent to give the amidopyrimidine; b) reacting the amidopyrimidine with a halogenating/cyclizing reagent to give a halopurine; c) reacting, in the presence of a base, the halopurine with an amine to give the substituted aminopurine; and d) closing the ring of the substituted aminopurine with a suitable dehydrating agent.
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(2008/06/13)

STEREOSELECTIVE SYNTHESIS OF OPTICALLY ACTIVE DIETHANOLOAMINES UTILIZING DIASTEREOSELECTIVE REACTION OF 1,3-OXAZOLIDINES WITH GRIGNARD REAGENTS
The highly diastereoselective addition of isopropoxydimethylsilylmethylmagnesium chloride to N-benzyl-1,3-oxazolidines derived from (R)-phenylglycinol, followed by oxidation of adducts with hydrogen peroxide in the presence of potassium fluoride, provided the 1-substituted (1R, 1'R)-N-benzyl-1'-phenyl-2,2'-dihydroxydiethylamines (1a-d).
Higashiyama, Kimio,Nakagawa, Katuyuki,Takahashi, Hiroshi
p. 2007 - 2018
(2007/10/03)

Synthesis of Optically Active 1,3,2-Oxazaphospholidine 2-Sulfides and 1,3,2-Benzodioxaphosphorin 2-Sulfides
The optical isomers of ten kinds of insecticidal 1,3,2-oxazaphospholidine 2-sulfides (OS) and two kinds of 1,3,2-benzodioxaphosphorin 2-sulfides (BS), including the commercial insecticide salithion, were synthesized in high optical purity by using two optically active aryl methyl phosphorochloridothionates (AMPC) as chiral two-step phosphorylating reagents.Their configurations were assigned according to the reaction mechanism and supported by proton NMR information.
Wu, Shao-Yong,Hirashima, Akinori,Kuwano, Eiichi,Eto, Morifusa
p. 537 - 548
(2007/10/02)

Selective preparation of isomers and enantiomers of cyclopropane carboxylic acids
A process has been discovered for selective preparation of isomers and enantiomers of 2,2-dimethyl-3-(2,2-dihalovinyl)cyclopropane carboxylic acids. In this process an adduct of an alkyl 3,3-dimethyl-4-pentenoate and a substituted 2-oxazolidone is reacted with a substituted dihalomethane compound. The resulting compound is cyclized, dehydrohalogenated and hydrolyzed to yield the desired product. These cyclopropane carboxylic acids are useful precursors for pyrethroid insecticides.
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(2008/06/13)

Ligand Exchange Chromatography of Amino Alcohols. Use of Schiff Bases in Enantiomer Resolution
A new method for enantiomeric resolution of primary amino alcohols by HPLC is described involving derivatization to the salicylaldehyde Schiff base followed by ligand exchange chromatography (LEC) with chiral L-proline-bonded stationary phases.All of the α-amino alcohols with a hydroxyl substituent on the asymmetric carbon examined were resolved, including catecholamines and other β-hydroxyphenethylamines.The copper(II) ion employed in LEC serves to stabilize the Schiff base, whereas the derivative permits complexation in a manner favorable for resolution and enhanced detection.A possible structure for the mixed complex responsible for separation is suggested.From this structure, a correlation between elution order and configuration is proposed.
Gelber, Loren R.,Karger, Barry L.,Neumeyer, John L.,Feibush, Binyamin
p. 7729 - 7734
(2007/10/02)

Stereochemistry and Reactions of Aziridinylphosphinothionates Derived from Amino Acids
Aziridinylphosphinothionates were prepared from optically active ethyl hydrogen phenylphosphonothionates and 1-bromo-2-alkanamines derived from leucine or valine.The aziridine ring was opened by the action of some nucleophiles.Refluxing the aziridinylphosphinethionates in acetone with sodium iodide caused hydrolysis accompanied by the rearrangement of the sulfur atom to give β-mercaptoethylphosphonamidates.The reaction mechanism was discussed eith stereochemical considerations.The insecticidal activity of the products was also examined.
Hirashima, Akinori,Eto, Morifusa
p. 829 - 838
(2007/10/02)