123534-00-9Relevant academic research and scientific papers
Reductive Elimination to Form C(sp3)-N Bonds from Palladium(II) Primary Alkyl Complexes
Peacock, D. Matthew,Jiang, Quan,Cundari, Thomas R.,Hartwig, John F.
, p. 3243 - 3247 (2018)
Reductive eliminations to form alkyl-nitrogen bonds are rare, and examples of this reaction from isolated complexes containing simple, unstabilized primary alkyl groups have not been observed. We report the synthesis of stable neopentylpalladium(II) anilido and methyleneamido complexes that undergo reductive elimination to form the C(sp3)-N bonds in N-neopentyl anilines and N-neopentyl imines, respectively. The synthesis and isolation of these complexes were enabled by weak chelation of palladium by P,O ancillary ligands. DFT calculations suggest that neopentylpalladium(II) complexes undergo reductive elimination by a concerted mechanism resembling a migration of the alkyl ligand to the nitrogen either following initial dissociation of the oxygen donor or in concert with lengthening of the Pd-O bond, depending on the identities of the reacting and ancillary ligands.
Ni-Catalyzed asymmetric reduction of α-keto-β-lactams: via DKR enabled by proton shuttling
Wang, Fangyuan,Tan, Xuefeng,Wu, Ting,Zheng, Long-Sheng,Chen, Gen-Qiang,Zhang, Xumu
supporting information, p. 15557 - 15560 (2020/12/30)
Chiral α-hydroxy-β-lactams are key fragments of many bioactive compounds and antibiotics, and the development of efficient synthetic methods for these compounds is of great value. The highly enantioselective dynamic kinetic resolution (DKR) of α-keto-β-lactams was realized via a novel proton shuttling strategy. A wide range of α-keto-β-lactams were reduced efficiently and enantioselectively by Ni-catalyzed asymmetric hydrogenation, providing the corresponding α-hydroxy-β-lactam derivatives with high yields and enantioselectivities (up to 92% yield, up to 94% ee). Deuterium-labelling experiments indicate that phenylphosphinic acid plays a pivotal role in the DKR of α-keto-β-lactams by promoting the enolization process. The synthetic potential of this protocol was demonstrated by its application in the synthesis of a key intermediate of Taxol and (+)-epi-Cytoxazone. This journal is
Asymmetric Petasis Borono-Mannich Allylation Reactions Catalyzed by Chiral Biphenols
Jiang, Yao,Schaus, Scott E.
supporting information, p. 1544 - 1548 (2017/02/05)
Chiral biphenols catalyze the asymmetric Petasis borono-Mannich allylation of aldehydes and amines through the use of a bench-stable allyldioxaborolane. The reaction proceeds via a two-step, one-pot process and requires 2–8 mole % of 3,3′-Ph2-BINOL as the optimal catalyst. Under microwave heating the reaction affords chiral homoallylic amines in excellent yields (up to 99 %) and high enantioselectivies (er up to 99:1). The catalytic reaction is a true multicomponent condensation reaction whereas both the aldehyde and the amine can possess a wide range of structural and electronic properties. Use of crotyldioxaborolane in the reaction results in stereodivergent products with anti- and syn-diastereomers both in good diastereoselectivities and enantioselectivities from the corresponding E- and Z-borolane stereoisomers.
Ir-Catalyzed C?H Amidation of Aldehydes with Stoichiometric/Catalytic Directing Group
Zhang, Yun-Fei,Wu, Bin,Shi, Zhang-Jie
supporting information, p. 17808 - 17812 (2016/11/28)
Ir-catalyzed sp2C?H amidation of aldehydes with various anilines as stoichiometric or catalytic directing groups was accomplished. A wide range of substrates were selectively amidated in good to excellent yields with broad functional group tolerance. The iridacycle complexes were isolated, characterized, and proved as key intermediates. Kinetic studies and Hammett plots provided detailed understandings of this amidation. According to the mechanism, the electron-rich ArSO2N3was proved effective for intermolecular sp3C?H amidation.
A general aminocatalytic method for the synthesis of aldimines
Morales, Sara,Guijarro, Fernando G.,Garcia Ruano, Jose Luis,Cid, M. Belen
supporting information, p. 1082 - 1089 (2014/02/14)
A general and efficient biomimetic method for the synthesis of aldimines from aldehydes and compounds bearing the NH2 group in the presence of pyrrolidine as a catalyst has been developed. These organocatalytic reactions, based on the application of the concept of nucleophilic catalysis, proceed with outstanding yields in the absence of acids and metals under simple conditions and minimum experimental manipulation. The method has been mainly applied to the synthesis of N-sulfinyl and N-sulfonyl imines, but its general validity has been proven with the preparation of representative N-phosphinoyl, N-alkyl, and N-aryl imines. These unprecedented reactions, which presumably occur via iminium activation without requiring acidic conditions, are an interesting and competitive alternative to the classical methods for preparing aldimines.
(+)-(S,S)-pseudoephedrine as a chiral auxiliary in asymmetric Mannich reactions: Scope and limitations
Iza, Ainara,Vicario, Jose L.,Carrillo, Luisa,Badia, Dolores
, p. 4065 - 4074 (2008/03/11)
The Mannich reaction of variously substituted (+)-(S,S)-pseudoephedrine amides with either enolizable and nonenolizable imines smoothly afforded a series of β-substituted α-alkyl-β-amino amides with full stereochemical control. These Mannich adducts have
New highly active taxoids from 9β-dihydrobaccatin-9,10-acetals. Part 5
Takeda, Yasuyuki,Uoto, Kouichi,Iwahana, Michio,Jimbo, Takeshi,Nagata, Motoko,Atsumi, Ryo,Ono, Chiho,Tanaka, Noriko,Terasawa, Hirofumi,Soga, Tsunehiko
, p. 3209 - 3215 (2007/10/03)
To improve the metabolic stability of 3, which exhibited both in vitro antitumor activity and in vivo efficacy by both iv and po administration, we designed and synthesized new taxane analogues. Most of the synthetic compounds maintained excellent antitum
The discovery of BMS-275183: An orally efficacious novel taxane
Mastalerz, Harold,Cook, Donald,Fairchild, Craig R.,Hansel, Steven,Johnson, Walter,Kadow, John F.,Long, Byron H.,Rose, William C.,Tarrant, James,Wu, Mu-Jen,Xue, May Quifen,Zhang, Guifen,Zoeckler, Mary,Vyas, Dolatrai M.
, p. 4315 - 4323 (2007/10/03)
The evolution of 2, a C-4-methylcarbonate analogue of paclitaxel with minimal oral bioavailability and oral efficacy, into its C-3′ -t-butyl-3′-N-t-butyloxycarbonyl analogue (15i), a novel taxane with oral efficacy in preclinical models that is comparable to iv administered paclitaxel, is described.
An electron paramagnetic resonance study of intermediates generated from aromatic aldimines
Nanni, Daniele,Pareschi, Patrizia,Walton, John C.
, p. 1098 - 1104 (2007/10/03)
It was shown by EPR spectroscopy that N-aryl-imines undergo hydrogen atom abstraction by tert-butoxyl radicals to generate imidoyl radicals in competition with addition to the C=N double bond to generate aminyl radicals. The latter were subsequently oxidised to nitroxides (aminoxyls) and also fragmented to release tert-butyl radicals and iminyl ethers. The main products identified were imines formed by combination of the imidoyl radicals with other radicals in the system. Thus, hydrogen abstraction is probably the most important homolytic pathway for the precursor imines. A similar reactivity pattern was found for N-tert-butyl-imines. DFT computations (B3LYP with a 6-31G* basis set) indicated that α-scissions of imidoyl radicals, ArN·C3R (R = t-Bu or Me), to produce isonitriles, ArNC, were too endothermic to occur under the present experimental conditions. tert-Butoxyl radicals were shown to add to 1-isocyano-4-chlorobenzene to generate N-arylimidoyl radicals that fragmented to afford 4-chloro-1-isocyanatobenzene.
