60027-61-4Relevant academic research and scientific papers
BABIPhos Family of Biaryl Dihydrobenzooxaphosphole Ligands for Asymmetric Hydrogenation
Li, Guisheng,Zatolochnaya, Olga V.,Wang, Xiao-Jun,Rodríguez, Sonia,Qu, Bo,Desrosiers, Jean-Nicolas,Mangunuru, Hari P. R.,Biswas, Soumik,Rivalti, Daniel,Karyakarte, Shuklendu D.,Sieber, Joshua D.,Grinberg, Nelu,Wu, Ling,Lee, Heewon,Haddad, Nizar,Fandrick, Daniel R.,Yee, Nathan K.,Song, Jinhua J.,Senanayake, Chris H.
supporting information, p. 1725 - 1729 (2018/04/14)
Novel bidentate phosphine ligands BABIPhos featuring a biaryl bis-dihydrobenzooxaphosphole core are presented. Their synthesis was achieved via Pd-catalyzed reductive homocoupling of dihydrobenzooxaphosphole aryl triflates. An efficient route toward various analogues was also established, giving access to phosphines with different electronic and steric properties. The newly obtained ligands demonstrated high efficiency and selectivity in Rh-catalyzed asymmetric hydrogenation of di- and trisubstituted enamides. This new class of ligands is complementary to previously described bidentate benzooxaphosphole ligands BIBOP.
The stereoselective construction of E- and Z-Δ-Ile from E-dehydroamino acid ester: the synthesis of the phomopsin A tripeptide side chain
Yasuno, Yoko,Nishimura, Akito,Yasukawa, Yoshifumi,Karita, Yuma,Ohfune, Yasufumi,Shinada, Tetsuro
supporting information, p. 1478 - 1481 (2016/01/25)
The stereoselective synthesis of the phomopsin A tripeptide side chain was achieved by using methyl 2-(((benzyloxy)carbonyl)amino)-2-(diphenoxyphosphoryl)acetate as a common synthetic precursor for the synthesis of E-Δ-dehydroisoleucine and E-Δ-aspartate.
Continuous-flow thermolysis for the preparation of vinylglycine derivatives
Lamborelle, Nicolas,Simon, Justine F.,Luxen, André,Monbaliu, Jean-Christophe M.
, p. 11602 - 11606 (2015/12/08)
Syn sulfoxide elimination was carried out under continuous-flow conditions in a mesofluidic thermolysis reactor. The design of the reactor enabled accurate control of reaction time and conditions, affording a convenient scale-independent procedure for the production of N,C-protected vinylglycine derivatives. Thermolysis at 270 °C under 1000 psi of pressure in superheated toluene enabled typical daily outputs ranging from 11 to 46 g per day with excellent selectivities and ee (>97%). The various competitive reaction pathways were studied and rationalized according to a computational study.
Stereoselective Synthesis of (E)-α,β-dehydroamino acid esters
Yasuno, Yoko,Hamada, Makoto,Yamada, Takeshi,Shinada, Tetsuro,Ohfune, Yasufumi
supporting information, p. 1884 - 1888 (2013/05/08)
Dehydroamino acid (Dhaa) is recognized as a useful tool or substrate for amino acid and peptide research. Although the stereoselective synthesis of the thermodynamically more stable Z-Dhaa has been well examined and established, the stereoselective synthesis of E-Dhaa has still remained to be a challenging synthetic task. In this paper, a stereoselective synthesis of E-Dhaa esters using a new (α-diphenylphosphono)glycine is described. The characteristic aspects of the new method are summarized as follows: (i) metal additives play an important role in the promotion of E-stereoselectivities. (ii) the use of NaI was effected for the synthesis of E-Dhaas bearing an aryl substituent and an amino functionality, (iii) MgBr2·OEt2 and ZnCl 2 contributed to improve the E-stereoselective synthesis of E-Dhaas bearing an alkyl substituent and an oxygen functionality, (iv) various protecting and functional groups were compatible under the reaction conditions, and (v) N-Cbz, Boc, and acyl-α-(diphenylphosphono)glycines were served for the stereoselective olefination reaction to provide the corresponding E-Dhaas. A variety of (E)-dehydroamino acid esters were stereoselectively synthesized by using (diphenylphosphono)glycinate. The stereoselectivity was influenced by metal additives. Various (E)-dehydroamino acid esters were prepared by the condensation reaction of the new phosphonates with easily available aldehydes by choosing the appropriate reaction conditions.
PREPARATION OF ALKENES BY MILD THERMOLYSIS OF SULFOXIDES
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Page/Page column 12; 13; 30, (2010/07/02)
Embodiments of this disclosure, among others, encompass methods for generating alkenes under mild thermolytic conditions that can provide almost total conversion of a precursor compound to an alkene without isomerization or the need to chromatographically purify the final product By selectively blocking the amino and carboxy groups of the depvatized amino acid, the methods of the disclosure provide for the synthesis of a peptide having the vinylglycine moiety at either the carboxy or the amino terminus of the peptide The mild conditions for the thermolytic removal of an o-NO2-phenyl substituted aryl group ensure that there is minimal if any damage to thermally sensitive conjugates such as a peptide bearing the vinylglycine The methods of the present disclosure have practical applications for the preparation of unsaturated compounds under mild, thermolytic conditions.
An improved protocol for the preparation of (S)-vinylglycine from (S)-methionine
Kuechenthal,Migenda, Julia,Polednia, Magdalena,Maison, Wolfgang
scheme or table, p. 443 - 448 (2010/11/17)
We present an optimized procedure for the synthesis of (S)-vinylglycine from (S)-methionine. The key step is a solvent free pyrolysis of an intermediate sulfoxide at high temperature. Using our optimized reaction conditions, Cbz-protected vinylglycine was
An improved procedure for the synthesis of dehydroamino acids and dehydropeptides from the carbonate derivatives of serine and threonine using tetrabutylammonium fluoride
Ramapanicker, Ramesh,Mishra, Roli,Chandrasekaran, Srinivasan
experimental part, p. 123 - 125 (2011/02/24)
Dehydroamino acids are important precursors for the synthesis of a number of unnatural amino acids and are structural components in many biologically active peptide derivatives. However, efficient synthetic procedures for their production in large amounts
Preparation of vinylglycines by thermolysis of homocysteine sulfoxides
Patel, Sravan Kumar,Long, Timothy E.
scheme or table, p. 5067 - 5070 (2009/12/01)
The synthesis and efficacy of preparing Cbz-VG-OMe (1) by thermolysis of alkyl and aryl homocysteine sulfoxides were surveyed. This investigation determined that aryl sulfoxide analogs were more effective for the reaction and that the 2-nitrophenyl analog 10f possessed a unique ability to syn eliminate at temperatures as low as 100 °C. The thermolysis of sulfoxide 10f was additionally discovered to occur under toluene reflux and when sodium acetate was added, Cbz-VG-OMe (1) could be obtained in high purity by simple filtration of the precipitated sulfenic acid byproduct 12. This mild protocol which was also applied in the synthesis of VG dipeptide 13 would have utility in the general synthesis of olefins and alkenes from 2-nitrophenylsulfoxides.
Simple and efficient synthesis of allo- and threo-3,3′-dimethylcystine derivatives in enantiomerically pure form
Nasir Baig,Sai Sudhir,Chandrasekaran, Srinivasan
, p. 1424 - 1428 (2008/12/20)
A simple and efficient method for the synthesis of allo- and threo-3,3′-dimethylcystine derivatives is reported. Various tosyl and bromo derivatives of Cbz-, Boc-, and Fmoc- protected threonine methyl esters have been prepared and subjected to nucleophili
Reactivity of dehydroamino acids and dehydrodipeptides towards N- bromosuccinimide: Synthesis of β-bromo- and β,β- dibromodehydroamino acid derivatives and of substituted 4-imidazolidinones
Ferreira, Paula M. T.,Monteiro, Luis S.,Pereira, Goreti,Ribeiro, Liliana,Sacramento, Joana,Silva, Liseta
, p. 5934 - 5949 (2008/09/17)
We have developed a modification of our previously reported high-yielding method for the synthesis of N,N-diacyldehydroamino acid derivatives to prepare N-monoprotected dehydroamino acids and dehydrodipeptides. Thus, several dehydroalanine, dehydroaminobutyric acid and dehydrophenylalanine derivatives have been prepared by treating the corresponding L-serine, L-threonine and D,L-3-phenylserine (threo-type) derivatives with 1 equiv. of di-tert-butyl dicarbonate and 4-(dimethylamino)pyridine. The reaction proceeded with the initial formation of an O-tert-butyl carbonate which, by treament with N,N,N′,N′-tetramethylguanidine, underwent β elimination to give the corresponding dehydroamino acid derivative. This two-step method can be carried out as a one-pot procedure and is stereoselective, giving only the Z isomer. The N-monoprotected dehydroamino acids were treated with N-bromosuccinimide and thereafter with triethylamine to afford several β,β-dibromodehydroalanines or β-bromo-, β-alkyl- or β-aryldehydroalanines. The latter were obtained as mixtures of E and Z isomers. An increased stereoselectivity towards the formation of the Z isomer was observed with dehydrophenylalanine and when 4-tolylsulfonyl was used as the N-protecting group. In the case of dehydrodipeptides, the reaction with NBS and triethylamine afforded the corresponding brominated dehydrodipeptides when the N-protecting group was other than 4-tolylsulfonyl. However, when the reagent was a peptide with a dehydroamino acid as the second residue and an N-(4-tolylsulfonyl) group the corresponding 2,2-disubstituted 1-(4-tolylsulfonyl)imidazolidin-4-ones were obtained in good-to-high yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
