123287-35-4Relevant articles and documents
Phosphite-Catalyzed C?H Allylation of Azaarenes via an Enantioselective [2,3]-Aza-Wittig Rearrangement
Motaleb, Abdul,Rani, Soniya,Das, Tamal,Gonnade, Rajesh G.,Maity, Pradip
supporting information, p. 14104 - 14109 (2019/09/06)
A phosphite-mediated [2,3]-aza-Wittig rearrangement has been developed for the regio- and enantioselective allylic alkylation of six-membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N-allyl salts undergo a stereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C?H functionalization of azaarenes. This method provides efficient access to tertiary and quaternary chiral centers in isoquinoline, quinoline, and pyridine systems, tolerating a broad variety of substituents on both the allyl part and azaarenes. Catalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.
Based on the chiral diamine spiro skeleton chiral phosphorus nitrile catalyst, preparation method and application thereof
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Paragraph 0074; 0077; 0078, (2017/08/16)
The invention provides a chiral phosphazene catalyst based on a spiro framework adopting chiral diamine, a preparation method and an application of the chiral phosphazene catalyst. The catalyst has a structure represented in the general formula: (RX-)3P=NR', chiral groups are introduced through R and R', and the catalyst has a structure with two seven-membered rings in centered connection through phosphorspirol. Optically pure tartaric acid or substituted hexahydrophthalic acid or 1,2-cyclopentanedicarboxylicacid,(1R,2S)-rel- is taken as a raw material, chiral diamine is generated through esterification, a Grignard reaction, an optional chlorination reaction, an azido reaction and a reduction reaction of the raw material, then chiral diamine and phosphorus pentachloride have a spirocyclization reaction to construct a phosphorspirol-centered screw ring, the chiral phosphazene molecular catalyst is obtained under the alkaline condition, and a method for substituting azido for hydroxyl directly has good application and popularization value. The catalyst has the advantages of high catalysis efficiency, good stereoselectivity, mild conditions, economy, environmental protection, simplicity and convenience in operation and the like as well as popularization and application prospects.
Novel tartrate-derived guanidine-catalyzed highly enantio- and diastereoselective Michael addition of 3-substituted oxindoles to nitroolefins
Zou, Liwei,Bao, Xiaoze,Ma, Yuanyuan,Song, Yuming,Qu, Jingping,Wang, Baomin
, p. 5760 - 5762 (2014/05/20)
The Michael addition of 3-substituted oxindoles to nitroolefins was catalyzed by a novel tartrate-derived guanidine in high yield with excellent diastereo- and enantioselectivity. This method showed an extraordinarily broad substrate scope in terms of both reaction partners. the Partner Organisations 2014.
Second example for the heterocomplexation of chiral diols and complete disproportionation of enantiomers for non-racemic 2,3-O-cyclohexylidene-1,1,4,4-tetraphenylthreitols
Hu, Xiaoyun,Shan, Zixing,Li, Wei
experimental part, p. 505 - 509 (2010/05/17)
Inclusion complexation of a tricyclic dipeptide derived from (S)-proline toward several chiral diols was examined, and observed that inclusion complexation behavior depended strongly on the composition of diol. For 2,3-O-alkylidene-1,1,4,4-tetraphenylthreitols, the derivatives of cyclohexanone and acetone reacted with the dipeptide to generate a 1:2 inclusion complex; however, the former is achiroselective, affording the second heterocomplex known to date. Based on the heterocomplexation, complete disproportionation of enantiomers of non-racemic 2,3-O-cyclohexylidene-1,1,4,4-tetraphenylthreitol was successfully realized, leading to highly effective separation of the excess enantiomer from the racemate. On the other hand, inclusion complexation did not occur between the dipeptide and rac-pinanediol or (4R,5R)-4-diphenylhydroxymethyl-5-hydroxy-2,6,6-triphenyl-1,3,2-dioxabor olane.
Design and evaluation of inclusion resolutions, based on readily available host compounds
Mueller, Simona,Afraz, Marcel Cyrus,De Gelder, Rene,Ariaans, Gerry J. A.,Kaptein, Bernard,Broxterman, Quirinus B.,Bruggink, Alle
, p. 1082 - 1096 (2007/10/03)
Resolution of enantiomers through selective crystallisation of diastereomeric inclusion compounds can extend the scope of traditional racemate resolution beyond salt forming compounds. To assess the practical value of this approach the literature was carefully screened and promising results were checked. Also an extensive range of new inclusion hosts suitable for resolution processes, derived from simple hydroxy- and amino acids were prepared and tested. Several techniques, including the Dutch Resolution approach utilizing mixtures of resolving agents, were applied. Over 70 potential resolving agents were tested in combinations with 34 racemates (over 100 racemates if literature results are included). Reproducibility of literature results was found to be problematic. Also the number of successful new resolutions found was very limited: only two efficient resolutions out of 1200 combinations of racemate and resolving agent tested in over 10.000 experiments! Crystal studies of representative combinations of resolving agents and inclusion compounds revealed some of the causes for the low rate of success in inclusion resolution. Compared to diastereomeric salts, the absence of strong electrostatic interactions substantially reduces the probability of forming crystals including both components. Molecular structure features allowing formation of intricate intramolecular and intermolecular H-bond networks were found to be responsible for inclusion crystal formation, and for the quality of the ensuing resolution through selective diastereomer crystallisation, in the successful cases. Whereas diastereomeric salt resolution continues to be of scientific and industrial interest, inclusion resolution should be viewed as of very limited scope; useful in specific instances, but lacking the wide applicability of classical resolution. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
Chiral Alkoxytitanium(IV) Complexes for Enantioselective Nucleophilic Additions to Aldehydes and as Lewis Acids in Diels-Alder Reactions
Seebach, Dieter,Beck, Albert K.,Imwinkelried, Rene,Roggo, Silvio,Wonnacott, Anne
, p. 954 - 974 (2007/10/02)
A number of chiral 1,2- 1,3-and 1,4-diols were prepared and used as alkoxy ligands on Ti for enantioselective nucleophilic transfer of methyl, butyl, cyclopropyl, allyl, alkinyl, and phenyl groups to aromatic adehydes, as wellas for the enantioselective cycloaddition of acrylate to cyclopentadiene.The 1,2-diols were pinane diol 7 and 1,2:5,6-diacetonide-protected mannitol 9 (Scheme 3) and tartrates.The 1,3-diols were obtained from the yeast-reduction products of 2-oxocyclopentane- and 2-oxocyclohexanecarboxylates and excess MeLi, BuLi, or PhLi (or the corresponding Grignard reagents; see 4-6).As 1,4-diols, we used the products 2 and 3 from tartrate acetals and methyl or phenyl Grignard reagents, the bis(benzaldehyde)acetal 8 of D-mannitol and o,o'-binaphthol (22).These diols were attached to the Ti-atom by azeotropic removal of i-PrOH from a mixture with .Addition of various organometallic reagents R-metal (metal=Li, BR3, MgX, MnCl, CuLiR) was followed by combination with aldehydes at -75 degC, a warmup period, quenching with aqueous KF solution, and workup (for results see Tables 1-6 and Formulae 17-20).The enantiomeric excess of the secondary alcohols obtained varies greatly, certain combinations of chiral ligands, nucleophilic groups, and aldehyde substrates give rise to values as high as 90 percent ee; see e.g.Table 4.The Ti-complexes of the general formula *O)2Cl2> or *O)2(i-PrO)Cl> induced the Diels-Alder addition of methyl acrylate to cyclopentadiene to take place at - 30 degC.The best enantioselectivity (50percentee) was observed with the binaphthol derivative (Table 7.) The structures of the complexes involved in these reactions are unknown.The substitution on C(2) of the dioxolanes 2 and 3 (derived from tartaric acid) has a pronounced effect on the selectivities of both reactions studied here (Tables 2,3, and 7).This remote effect (1,6-distance between the stereogenic acetal-C-atom and the Ti-centers) must be caused by conformational changes in the vicinity of the reactive site, i.e. the Ti-C bond in the nucleophilic addition reactions and the Ti-acrylate-oxygen complexation in the Diels-Alder reaction.
