70396-37-1Relevant 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.
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.
PREPARATION OF ALKENES BY MILD THERMOLYSIS OF SULFOXIDES
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Page/Page column 11; 29, (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
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.
Enantioselective Synthesis of Non-Natural Aromatic α-Amino Acids
Krebs, Andreas,Ludwig, Verena,Pfizer, Jose,Duerner, Gerd,Goebel, Michael W.
, p. 544 - 553 (2007/10/03)
We present two complementary methods for the stereoselective synthesis of non-natural α-amino acids with aromatic or heteroaromatic side chains. One approach is based on the chemical transformation of methionine, whereas the other applies the stereoselective Myers alkylation of glycine. The resulting product types differ in the linker length between glycine and the aromatic substituent. Since methionine and pseudoephedrine are available in both absolute configurations, R- or S-configured enantiopure amino acids with either C2 or C3 linkers can be obtained on gram scales. In each case the key step of the synthesis is hydroboration of the unsaturated building blocks 9 and 17, followed by palladium-catalyzed Suzuki cross-coupling with aryl halides. Attention must in certain cases be paid to the stereochemical integrity when basic Suzuki conditions are applied. Our initial difficulties are reported as well as the final "racemization-proof" procedures. The protecting groups chosen for the α-amino acids should be compatible with solid-phase peptide synthesis. This was confirmed by the successful synthesis of a series of tripeptides.
DEHYDRATION OF β-HYDROXY-α-AMINO ACID DERIVATIVES WITH PHENYLTRIFLIMIDE
Torrini, Ines,Zecchini, Giampiero Pagani,Paradisi, Mario Paglialunga
, p. 695 - 704 (2007/10/02)
Conversion of N-protected β-hydroxy-α-amino esters to corresponding didehydroamino esters have been achieved using phenyltriflimide/triethylamine as a mild dehydrating agent.The selective formation of didehydroalanine derivatives from dipeptides containin
