146476-35-9Relevant academic research and scientific papers
Tunable Bifunctional Phosphine-Squaramide Promoted Morita-Baylis-Hillman Reaction of N-Alkyl Isatins with Acrylates
Dong, Ze,Yan, Chao,Gao, Yongzhi,Dong, Chune,Qiu, Guofu,Zhou, Hai-Bing
, p. 2132 - 2142 (2015/06/23)
A series of highly tunable bifunctional phosphine-squaramide H-bond donor organocatalysts 6 has been synthesized from inexpensive and commercially available β-amino alcohols in moderate yields. Catalyst 6 can efficiently promote the asymmetric Morita-Baylis-Hillman (MBH) reaction of N-alkyl isatins with acrylate esters providing the chiral 3-substituted 3-hydroxy-2-oxindoles in good yields and enantioselectivities (up to 93 yield and 95 ee), in which the challenging substrate tert-butyl acrylate 9d, provided the best ee value to date. Moreover, this methodology was applied successfully in the synthesis of chiral cyclic spiropyrrolizidineoxindole and γ-butyrolactone derivatives without enantioselectivity deterioration. The possible mechanism of this MBH reaction was also investigated by 31PNMR, ESI-MS and KIE studies. The KIE experiments show that the electrophilic addition of N-methyl isatin to the complex of acrylate ester and phophine-squaramide is the rate-determing step of the asymmetric MBH reaction.
Synthesis of iron P-N-P' and P-NH-P asymmetric hydrogenation catalysts
Sonnenberg, Jessica F.,Lough, Alan J.,Morris, Robert H.
supporting information, p. 6452 - 6465 (2015/02/19)
Complexes of the type mer,trans-[Fe(P-N-P)(CO)2Br]BF4 are known to be precatalysts for the asymmetric direct hydrogenation of ketones and imines. Employing related ligand scaffolds, we successfully generated and tested the series of three new precatalysts [Fe(PCy2CH2CH-NCH(R)CH2PPh2)(CO)2Br]BF4 with chirality derived from (S)-amino alcohols with phenyl, benzyl, and isopropyl substituents (R), yielding fairly active and selective systems. For the reduction of acetophenone to (S)-1-phenylethanol turnover frequencies up to 920 h-1 and up to 74% enantiomeric excess at 50 °C and 5-25 atm of H2 were obtained. We found, however, that placing these large groups R next to nitrogen was found to be deleterious to catalytic activity. Extending the scope of the ligand structure, we then developed a series of six P-N-P and five P-NH-P systems starting with o-diphenylphosphinobenzaldehyde and the phosphine-amines PPh2CHR1CHR2NH2 (R1 = H, Ph, CH2Ph, iPr with R2 = H or R1 = Me, Ph with R2 = Ph) as well as their corresponding [Fe(P-N-P)(NCMe)3][BF4]2 and [Fe(P-NH-P)(NCMe)3][BF4]2 complexes, which were not catalytically active. Finally, we made the new achiral iron complex mer,cis-Fe(PPh2(o-C6H4)CHNCH2CH2PPh2)(CO)Br2, which was active for the direct hydrogenation of acetophenone, achieving turnover frequencies of 800 h-1 at 50°C and 25 atm of H2.
Catalytic asymmetric [4+2] annulation initiated by an aza-rauhut-currier reaction: Facile entry to highly functionalized tetrahydropyridines
Shi, Zugui,Yu, Peiyuan,Loh, Teck-Peng,Zhong, Guofu
supporting information; experimental part, p. 7825 - 7829 (2012/09/08)
Under control: The first example of chiral amino phosphine catalysts for the title reaction between vinyl ketones and N-sulfonyl-1-aza-1,3-dienes has been developed. Under ambient conditions, this protocol provides straightforward access to densely functionalized, enantioenriched tetrahydropyridines with high levels of sterecontrol in good to excellent yields. Copyright
L-Threonine-derived novel bifunctional phosphine-sulfonamide catalyst-promoted enantioselective aza-morita-Baylis-Hillman reaction
Zhong, Fangrui,Wang, Youqing,Han, Xiaoyu,Huang, Kuo-Wei,Lu, Yixin
supporting information; experimental part, p. 1310 - 1313 (2011/04/26)
A series of novel bifunctional phosphine-sulfonamide organic catalysts were designed and readily prepared from natural amino acids, and they were utilized to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions. l-Threonine-derived phosphine
Enantioselective Morita-Baylis-Hillman reaction promoted by l-threonine-derived phosphine-thiourea catalysts
Han, Xiaoyu,Wang, Youqing,Zhong, Fangrui,Lu, Yixin
supporting information; experimental part, p. 6734 - 6740 (2011/11/05)
A series of bifunctional phosphine-thiourea organic catalysts based on natural amino acid scaffolds were designed and prepared. l-Threonine-derived bifunctional phosphine catalysts were found to be very efficient in promoting asymmetric Morita-Baylis-Hillman (MBH) reaction of acrylates with aromatic aldehydes, affording the desired MBH adducts with up to 90% ee. To gain mechanistic insights into the reaction, the effects of adding various additives on the MBH reaction were investigated. We propose that the hydrogen bonding interactions between the thiourea moiety of the catalyst and the enolate intermediate are crucial for the stereochemical outcome of the reaction. The method described in this report may provide a practical solution to the enantioselective MBH reaction of simple acrylates.
Synthesis of chiral aminophosphines from chiral aminoalcohols via cyclic sulfamidates
Guo, Rongwei,Lu, Shuiming,Chen, Xuanhua,Tsang, Chi-Wing,Jia, Wenli,Sui-Seng, Christine,Amoroso, Dino,Abdur-Rashid, Kamaluddin
supporting information; experimental part, p. 937 - 940 (2010/05/02)
(Chemical Equation Presented) Protic aminophosphines with multiple chiral centers were synthesized in good yields and high purity by the nucleophilic ring-opening of N-protected cyclic sulfamidates with metal phosphides, followed by hydrolysis and deprote
Investigation of the importance of nitrogen substituents in a N-P chiral ligand for enantioselective allylic alkylation
Anderson, James C.,Cubbon, Rachel J.,Harling, John D.
, p. 923 - 935 (2007/10/03)
The synthesis of three chiral chelate nitrogen-phosphorus (S)-valine derived ligands with the potential for stereogenic nitrogen donation is described. In palladium catalysed allylic substitution reactions the ligands induced varying enantioselectivities ranging from 92% e.e. of the (R)-enantiomer to 83% e.e. of the (S)-enantiomer. Structural and spectroscopic investigations into the origin of this effect were conducted, but were inconclusive. However, the importance of the consideration of N-substituents in such systems is highlighted.
A new class of C2-symmetric diphosphine ligands derived from valine: Remarkably diverse behavior in catalytic asymmetric transformations
Saitoh, Akihito,Uda, Takashi,Morimoto, Toshiaki
, p. 4501 - 4511 (2007/10/03)
A new C2-symmetric diphosphine ligand 8a was readily prepared in one step by treatment of the synthetic precursor of VALAP, 7, with phthaloyl chloride. Remarkably high levels of asymmetric induction, over 99% ee, were achieved using 8a in palladium-catalyzed asymmetric allylic transformations of sterically less demanding cyclohexenyl substrates 9. The ligand system was easily extended to the development of analogous chiral auxiliaries 8b,c by the identical procedure but using isophthaloyl chloride and succinyl chloride. However, the ligands 8b,c exhibited much lower catalytic activity. In contrast to the asymmetric allylic substitutions, 8c demonstrated significant improvement of enantioselectivity, up to 64% ee, in rhodium- catalyzed asymmetric hydrosilylations of acetophenone 11a compared to 35% ee using 8a. In this way, the versatility of the present ligand system played an important role in variations of substrates and reaction types. (C) 1999 Elsevier Science Ltd.
A phosphorus-containing chiral amidine ligand for asymmetric reactions: Enantioselective Pd-catalyzed allylic alkylation
Saitoh, Akihito,Morimoto, Toshiaki,Achiwa, Kazuo
, p. 3567 - 3570 (2007/10/03)
Phosphorus-containing amidine 7 was prepared through several steps from L-valine 1. The new ligand for asymmetric reactions was evaluated in the palladium-catalyzed allylic alkylation of 1,3-diphenylprop-2-enyl acetate and pivalate 8a,b with the nucleophile derived from dimethyl malonate as a preliminary study. Excellent levels of asymmetric induction up to 95% e.e. were achieved along with an efficient conversion.
Synthesis of (β-N-sulfonylaminoalkyl)phosphines and their use in palladium-mediated asymmetric synthesis
Sakuraba,Okada,Morimoto,Achiwa
, p. 927 - 934 (2007/10/02)
A series of (β-N-sulfonylaminoalkyl)phosphine ligands has been developed and employed for asymmetric palladium-catalyzed hydrosilylation and Heck-type hydroarylation, affording up to 72% ee and 90% yield.
