161671-34-7Relevant articles and documents
Deprotection of N-tert-butoxycarbonyl (Boc) groups in the presence of tert-butyl esters
Lin,Lanza T.,De Laszlo,Truong,Kamenecka,Hagmann
, p. 7013 - 7016 (2000)
Deprotection of Boc groups in the presence of tert-butyl esters was achieved by using concentrated H2SO4 (1.5-3.0 equiv.) in tBuOAc or MeSO3H (1.5-3.0 equiv.) in tBuOAc:CH2Cl2 (4:1 v/v). The yields ranged from 70 to 100% for a variety of amino acid and dipeptide substrates. (C) 2000 Elsevier Science Ltd.
Structure tuning of lithium amide for asymmetric 1,4-addition to cinnamate and subsequent demasking
Sakai, Takeo,Doi, Hirohisa,Kawamoto, Yoshito,Yamada, Ken-Ichi,Tomioka, Kiyoshi
, p. 9261 - 9263 (2004)
Systematic structure tuning of lithium amides derived from benzyl-N-TMS-, allyl-N-TBDMS-, and diisopropylamines lead to several candidates including anthracen-9-ylmethanamine which provided high performance in the enantioselective 1,4-addition (91% ee) an
Asymmetric addition of Reformatsky-type reagent to imines utilizing diisopropyl tartrate as a chiral auxiliary
Ukaji, Yutaka,Takenaka, Shoichi,Horita, Yoshie,Inomata, Katsuhiko
, p. 254 - 255 (2001)
The asymmetric nucleophilic addition of Reformatsky-type reagent to imines, which were prepared from aldehydes and 2-aminophenols, was achieved by the use of diisopropyl (R,R)-tartrate as a chiral auxiliary to afford the corresponding β-amino acid ester derivatives with excellent enantioselectivities. In order to realize reproducible higher stereoselection, the addition of a small amount of water was crucial.
Acylation of β-Amino Esters and Hydrolysis of β-Amido Esters: Candida antarctica Lipase A as a Chemoselective Deprotection Catalyst
M?enp??, Harri,Kanerva, Liisa T.,Liljeblad, Arto
, p. 1226 - 1232 (2016/04/05)
N-Acylation by lipase A from Candida antarctica (CAL-A) in ethyl butanoate was applied to the kinetic resolution of tert-butyl esters of 3-amino-3-phenylpropanoic acid (E>100), 3-amino-4-methylpentanoic acid (E>100) and 3-aminobutanoic acid (E=60) on 1.0-2.0 m scale. With the N-acylated resolution products, the exceptional ability of CAL-A to hydrolyse amides and bulky tert-butyl esters was then studied. In all N-acylated tert-butyl esters, chemoselectivity favoured the amide bond cleavage. The tert-butyl ester bond was left intact with 3-amino-3-phenylpropanoate, whereas with 3-amino-4-methylpentanoate and 3-aminobutanoate the CAL-A-catalysed hydrolysis of tert-butyl ester followed the amide hydrolysis.
A chiral ligand mediated aza-conjugate addition strategy for the enantioselective synthesis of β-amino esters that contain hydrogenolytically sensitive functionality
Archer, Robert M.,Hutchby, Marc,Winn, Caroline L.,Fossey, John S.,Bull, Steven D.
, p. 8838 - 8847 (2015/10/20)
Aza-conjugate addition of the lithium anion of N-trimethylsilyl-p-methoxybenzylamine to tert-butyl enoate acceptors, in the presence of a stoichiometric amount of enantiopure 1,2-dimethoxy-1,2-diphenylethane and excess trimethylsilyl chloride, affords ter
Asymmetric michael addition of a recyclable chiral amine: Inversion of stereoselectivity caused by the difference of ethereal solvents
Node, Manabu,Hashimoto, Daisuke,Katoh, Takahiro,Ochi, Shunsuke,Ozeki, Minoru,Watanabe, Tsunefumi,Kajimoto, Tetsuya
supporting information; experimental part, p. 2653 - 2656 (2009/05/27)
(Chemical Equation Presented) The Michael addition of a chiral amine [(-)-6] to α,β-unsaturated esters (4) was attained and the stereoselectivity was inverted by changing the solvent from diethyl ether to tetrahydrofuran when α,β-unsaturated esters having an aromatic ring at the β-position were employed. In addition, the chiral auxiliary in the Michael adducts (9A) was facilely removed with N-iodosuccinimide to afford β-amino esters (10A) and 2-methoxy-d-bornylaldehyde (11), which can be reclaimed to the chiral amine (6) by reductive amination.
Parallel synthesis of homochiral β-amino acids
Davies, Stephen G.,Mulvaney, Andrew W.,Russell, Angela J.,Smith, Andrew D.
, p. 1554 - 1566 (2008/02/09)
The parallel asymmetric synthesis of an array of 30 β-amino acids of high enantiomeric purity using the conjugate addition of homochiral lithium N-benzyl-N-(α-methylbenzyl)amide as the key step is accomplished. The experimental simplicity and highly practical nature of the protocol is demonstrated by the efficient parallel conversion of 15 α,β-unsaturated esters to both enantiomeric series of the corresponding β-amino acids in high overall yields and selectivities with minimal purification involved in each step of the reaction protocol.
Chiral ligand-controlled asymmetric conjugate amination of enoates with lithium mesitylmethyl(trimethylsilyl)amide
Sakai, Takeo,Doi, Hirohisa,Tomioka, Kiyoshi
, p. 8351 - 8359 (2007/10/03)
Lithium mesitylmethyl(trimethylsilyl)amide behaved as a nice amination agent in a chiral ligand-controlled conjugate addition reaction of tert-butyl cinnamate to give the conjugate amination product with 99% ee in 90% yield. Other acyclic and cyclic enoat
Homochiral lithium amides for the asymmetric synthesis of β-amino acids
Davies, Stephen G.,Garrido, Narciso M.,Kruchinin, Dennis,Ichihara, Osamu,Kotchie, Luke J.,Price, Paul D.,Mortimer, Anne J. Price,Russell, Angela J.,Smith, Andrew D.
, p. 1793 - 1811 (2007/10/03)
Secondary homochiral lithium amides derived from α-methylbenzylamine undergo highly diastereoselective conjugate additions to a range of α,β-unsaturated esters. The corresponding β-amino acids are readily liberated by successive N-debenzylation and ester hydrolysis, furnishing (R)-β-amino butyric acid, (R)-β-amino pentanoic acid, (S)-β-leucine, (R)-β-amino octanoic acid, (S)-β-phenylalanine, (S)-β-tyrosine methyl ether, (S)-β-tyrosine hydrochloride and (S)-β-(2-methoxyphenyl)-β-amino propanoic acid in high yields and high ee. The application of this procedure to the synthesis of the natural products (R)-β-DOPA and (R)-β-lysine is demonstrated. The development of a simplified one-pot reaction protocol applicable to the multi-gram scale synthesis of homochiral β-amino esters is also delineated.
Asymmetric synthesis of intermediates for otamixaban and premafloxacin by the chiral ligand-controlled asymmetric conjugate addition of a lithium amide
Sakai, Takeo,Kawamoto, Yoshito,Tomioka, Kiyoshi
, p. 4706 - 4709 (2007/10/03)
A chiral ligand-controlled conjugate addition reaction of lithium benzyl(trimethylsilyl)amide with tert-butyl enoates gave the corresponding lithium enolates that were then treated with electrophiles, giving anti-alkylation products with high ee up to 98%. The benzyl group on the amino nitrogen was removed by the oxidation of secondary amines to imines and subsequent transoximation to give 3-aminoalkanoates in good yields. The products are the possible key intermediates of otamixaban and premafloxacin.
