100007-62-3Relevant articles and documents
A new strategy for designing non-C2-symmetric monometallic bifunctional catalysts and their application in enantioselective cyanation of aldehydes
Yang, Fei,Wei, Siping,Chen, Chien-An,Xi, Peihua,Yang, Li,Lan, Jingbo,Gau, Han-Mou,You, Jingsong
, p. 2223 - 2231 (2008)
A monometallic bifunctional catalyst, in which only one imidazolyl moiety is directly attached at the 3-position of a binaphthol moiety, has been developed. The ligand (R)-1, which lacks C2-symmetry and flexible linkers, in combination with Ti(OiPr)4, has been demonstrated to promote the enantioselective cyanation of aldehydes with trimethylsilylcyanide (TMSCN), giving excellent enantioselectivities of up to 98 % ee and high yields of up to 99%. The use of this bifunctional catalytic system obviates the need for additives and is extremely simple as the reagents are added in one portion at the beginning of the reaction. The protocol has been found to tolerate a relatively wide range of aldehydes when 10 mol% of the (R)-1/Ti(OiPr) 4 complex is deployed in CH2Cl2 at -40°C, the conditions which proved most practical and effective. The asymmetric cyanations also proceeded with lower catalyst loadings (5 mol%, or even 2 mol%), still giving satisfactory enantiomeric excesses and yields. Interestingly, the use of freshly distilled TMSCN dried over CaH2 gave a low enantioselectivity and only a moderate yield of the adduct as compared with direct use of the commercial reagent. The results of 13C NMR spectroscopic studies implicate HCN as the actual reactive nucleophile.
Asymmetric trimethylsilylcyanation of aldehydes utilizing chiral bismuth compounds. A frontier in bismuth mediated synthetic reactions
Wada, Makoto,Takahashi, Toshikazu,Domae, Terutomo,Fukuma, Tomohiro,Miyoshi, Norikazu,Smith, Keith
, p. 3939 - 3946 (1997)
Bismuth(III) chloride (BiCl3) was found to work efficiently as a versatile catalyst for cyanation of aldehydes with trimethylsilyl cyanide to afford the corresponding cyanohydrins in high yields. Triphenylbismuthan (Ph3Bi) is also effective. The reaction has been applied to the asymmetric cyanation of a variety of aldehydes in high yields with moderate to good enantioselectivities by use of a chiral bismuth catalyst prepared in situ from BiCl3 and (2R,3R)-(+)-diethyl tartrate.
Enantioselective trimethylsilylcyanation of aldehydes
Bolm, Carsten,Mueller, Peter
, p. 1625 - 1628 (1995)
A chiral titanium reagent derived from optically active sulfoximine (R)-3 and Ti(O-i-Pr)4 promotes the asymmetric addition of trimethylsilylcyanide to aldehydes affording cyanohydrins in high yields with good enantioselectivities (up to 91% ee).
Cyanosilylation of aldehydes catalyzed by N-heterocyclic carbenes
Suzuki, Yumiko,Bakar, M.D., Abu,Muramatsu, Kazuyuki,Sato, Masayuki
, p. 4227 - 4231 (2006)
N-Heterocyclic carbenes produced in situ from salts of imidazolium, benzimidazolium, pyrido[1,2-c]imidazolium, imidazolinium, thiazolium, and triazolium catalyze the addition of trimethylsilylcyanide to aldehydes to yield cyanohydrin trimethylsilyl ethers. The use of C2-symmetric imidazolidenyl carbene derived from (R,R)-1,3-bis[(1-naphthyl)ethyl]imidazolium chloride led to enantioselective cyanosilylation.
Enantioselective synthesis of aliphatic cyanohydrin acetates
Veum, Lars,Hanefeld, Ulf
, p. 2382 - 2384 (2005)
When the standard conditions for the enantioselective synthesis of cyanohydrin acetates via dynamic kinetic resolution are applied to aliphatic substrates, only a kinetic resolution is observed. However, by exchanging the base (Amberlite) against NaCN, qu
The Asymmetric Hydrocyanation of Aldehydes with Cyanotrimethylsilane Promoted by a Chiral Titanium Reagent
Narasaka, Koichi,Yamada, Tohru,Minamikawa, Hiroyuki
, p. 2073 - 2076 (1987)
The asymmetric hydrocyanation of aldehydes with cyanotrimethylsilane proceeds by the use of a chiral alkoxy titanium(IV) to give the corresponding cyanohydrins with good enantioselectivity.
An N-heterocyclic carbene as a nucleophilic catalyst for cyanosilylation of aldehydes
Fukuda, Yoshimasa,Maeda, Yuka,Ishii, Satoru,Kondo, Kazuhiro,Aoyama, Toyohiko
, p. 589 - 590 (2006)
The first method for cyanosilylation of aldehydes with trimethylsilyl cyanide in the presence of the N-heterocyclic carbene prepared from 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride and potassium tert-butoxide, as a nucleophilic catalyst, is described. Georg Thieme Verlag Stuttgart.
Lanthanoid(III) Alkoxides as Novel Catalysts for a Rapid Transhydrocyanation from Acetone Cyanohydrin to Aldehydes and Ketones
Ohno, Hiroshi,Mori, Atsunori,Inoue, Shohei
, p. 375 - 378 (1993)
A rapid transhydrocyanation from acetone cyanohydrin to several aldehydes and ketones is promoted by a catalytic amount of lanthanoid(III) alkoxide to provide the corresponding cyanohydrins.
Highly enantioselective cyanosilylation of aldehydes catalyzed by a chiral oxazaborolidinium ion
Ryu, Do Hyun,Corey
, p. 8106 - 8107 (2004)
The chiral oxazaborolidinium salts 1 and 2 are excellent catalysts for the enantioselective cyanosilylation of a wide variety of aldehydes (see Table 1) using trimethylsilyl (TMS) cyanide and triphenylphosphine oxide as the source of a new reactive cyanide donor. This donor appears to be the isocyanophosphorane Ph3P(OTMS)(N=C:) (4). The novel process described herein has several advantages: predictability of absolute configuration of cyanohydrin products from a mechanistic model (3), high yields and very good enantiomeric purity of products (≥90%), and, finally, easy and efficient recovery of the catalytic ligand. Copyright
Preparation of polystyrene-bound dichlorotitanium dialkoxide and its application as a polymer-supported Lewis acid catalyst in organic syntheses
Fujita, Ken-Ichi,Muraki, Takahito,Hashimoto, Shigeru,Oishi, Akihiro,Taguchi, Yoichi
, p. 2097 - 2098 (2004)
Polymer-supported dichlorotitanium dialkoxide was readily prepared from polystyrene-bound α-glycol and dichlorotitanium diisopropoxide. When we employed it as an immobilized Lewis acid catalyst, several fundamental and important Lewis acid-catalyzed react
Br?nsted Acid-Catalyzed Cyanotritylation of Aldehydes by Trityl Isocyanide
Cioc, Rǎzvan C.,Schuckman, Peter,Preschel, Hans D.,Vlaar, Tj?stil,Ruijter, Eelco,Orru, Romano V.A.
, p. 3562 - 3565 (2016)
Cyanohydrins are versatile intermediates toward valuable organic compounds like α-hydroxy carboxylic acids, α-amino acids, and β-amino alcohols. Numerous protocols are available for synthesis of (O-protected) cyanohydrins, but all procedures invariably rely on the use of toxic cyanide sources. A novel cyanide-free synthesis of O-trityl protected cyanohydrins via a catalytic Passerini-type reaction involving aldehydes and trityl isocyanide is reported. The feasibility of a catalytic asymmetric reaction is demonstrated using chiral phosphoric acid catalysis.
Enantioselective silylcyanation of aldehydes catalyzed by new chiral oxovanadium complex
Chu, Chang-Ying,Hsu, Chu-Tin,Lo, Po Hsiang,Uang, Biing-Jiun
, p. 1981 - 1984 (2011)
Oxovanadium(V) complex 4 was prepared from VOSO4 and tridentate Schiff base ligand, which was prepared from substituted salicylaldehyde and inexpensive (S)-valine. Asymmetric silylcyanation of the aldehydes catalyzed by catalyst 4 afforded cyanohydrins with good enantioselectivities.
A High-Throughput Screening Method for the Directed Evolution of Hydroxynitrile Lyase towards Cyanohydrin Synthesis
Zheng, Yu-Cong,Ding, Liang-Yi,Jia, Qiao,Lin, Zuming,Hong, Ran,Yu, Hui-Lei,Xu, Jian-He
, p. 996 - 1000 (2021/01/15)
Chiral cyanohydrins are useful intermediates in the pharmaceutical and agricultural industries. In nature, hydroxynitrile lyases (HNLs) are a kind of elegant tool for enantioselective hydrocyanation of carbonyl compounds. However, currently available methods for demonstrating hydrocyanation are still stalled at precise, but low-throughput, GC or HPLC analyses. Herein, we report a chromogenic high-throughput screening (HTS) method that is feasible for the cyanohydrin synthesis reaction. This method was highly anti-interference and sensitive, and could be used to directly profile the substrate scope of HNLs either in cell-free extract or fermentation clear broth. This HTS method was also validated by generating new variants of PcHNL5 that presented higher catalytic efficiency and stronger acidic tolerance in variant libraries.
Enantioconvergent Cu-Catalyzed Radical C-N Coupling of Racemic Secondary Alkyl Halides to Access α-Chiral Primary Amines
Cheng, Jiang-Tao,Dong, Xiao-Yang,Gu, Qiang-Shuai,Li, Zhong-Liang,Liu, Juan,Liu, Xin-Yuan,Luan, Cheng,Wang, Fu-Li,Wang, Li-Lei,Yang, Ning-Yuan,Zhang, Yu-Feng
supporting information, p. 15413 - 15419 (2021/09/30)
α-Chiral alkyl primary amines are virtually universal synthetic precursors for all other α-chiral N-containing compounds ubiquitous in biological, pharmaceutical, and material sciences. The enantioselective amination of common alkyl halides with ammonia is appealing for potential rapid access to α-chiral primary amines, but has hitherto remained rare due to the multifaceted difficulties in using ammonia and the underdeveloped C(sp3)-N coupling. Here we demonstrate sulfoximines as excellent ammonia surrogates for enantioconvergent radical C-N coupling with diverse racemic secondary alkyl halides (>60 examples) by copper catalysis under mild thermal conditions. The reaction efficiently provides highly enantioenrichedN-alkyl sulfoximines (up to 99% yield and >99% ee) featuring secondary benzyl, propargyl, α-carbonyl alkyl, and α-cyano alkyl stereocenters. In addition, we have converted the masked α-chiral primary amines thus obtained to various synthetic building blocks, ligands, and drugs possessing α-chiral N-functionalities, such as carbamate, carboxylamide, secondary and tertiary amine, and oxazoline, with commonly seen α-substitution patterns. These results shine light on the potential of enantioconvergent radical cross-coupling as a general chiral carbon-heteroatom formation strategy.
Visible-Light-Driven N-Heterocyclic Carbene Catalyzed γ- and ?-Alkylation with Alkyl Radicals
Dai, Lei,Xia, Zi-Hao,Gao, Yuan-Yuan,Gao, Zhong-Hua,Ye, Song
supporting information, p. 18124 - 18130 (2019/11/13)
The merging of photoredox catalysis and N-heterocyclic carbene (NHC) catalysis for γ- and ?-alkylation of enals with alkyl radicals was developed. The alkylation reaction of γ-oxidized enals with alkyl halides worked well for the synthesis γ-multisubstituted-α,β-unsaturated esters, including those with challenging vicinal all-carbon quaternary centers. The synthesis of ?-multisubstituted-α,β-γ,δ-diunsaturated esters by an unprecedented NHC-catalyzed ?-functionalization was also established.
