61428-00-0Relevant academic research and scientific papers
Switch in Selectivity for Formal Hydroalkylation of 1,3-Dienes and Enynes with Simple Hydrazones
Li, Chao-Jun,Lv, Leiyang,Qiu, Zihang,Yu, Lin
, p. 6466 - 6472 (2020)
Controlling reaction selectivity is a permanent pursuit for chemists. Regioselective catalysis, which exploits and/or overcomes innate steric and electronic bias to deliver diverse regio-enriched products from the same starting materials, represents a powerful tool for divergent synthesis. Recently, the 1,2-Markovnikov hydroalkylation of 1,3-dienes with simple hydrazones was reported to generate branched allylic compounds when a nickel catalyst was used. As part of the effort, shown here is that a complete switch of Markovnikov to anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes.
Nickel-catalyzed cross-coupling of umpolung carbonyls and alkyl halides
Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
, (2019/05/22)
An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
Nickel-Catalyzed Cross-Coupling of Umpolung Carbonyls and Alkyl Halides
Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
, p. 6312 - 6322 (2019/05/24)
An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
Denitrogenative Hydrotrifluoromethylation of Benzaldehyde Hydrazones: Synthesis of (2,2,2-Trifluoroethyl)arenes
Zhao, Zhensheng,Ma, Kevin C. Y.,Legault, Claude Y.,Murphy, Graham K.
supporting information, p. 11240 - 11245 (2019/08/20)
Reacting hydrazones of arylaldehydes with Togni's CF3-benziodoxolone reagent, in the presence of potassium hydroxide and cesium fluoride, induces a denitrogenative hydrotrifluoromethylation event to produce (2,2,2-trifluoroethyl)arenes. This novel reaction was tolerant to many electronically-diverse functional groups and substitution patterns, as well as naphthyl- and heteroaryl-derived substrates. Advantages of this process include the easy access to hydrazone precursors on a large scale, speed and operational simplicity, and being transition metal-free.
Umpolung cross-coupling of polyfluoroarenes with hydrazones: Via activation of C-F bonds
Cao, Dawei,Pan, Pan,Zeng, Huiying,Li, Chao-Jun
supporting information, p. 9323 - 9326 (2019/08/08)
An umpolung strategy for the cross-coupling of polyfluoroarenes with various substituted hydrazones to construct C(sp2)-C(sp3) bonds is developed. In this strategy, the C-F bond of polyfluoroarenes is cleaved and coupled with moisture- and air-stable hydrazones under mild conditions with good to excellent yields. This method provides a useful tool for synthesizing polyfluorinated pharmaceuticals and functional materials.
Nickel-catalyzed cross-coupling of aldehydes with aryl halides: Via hydrazone intermediates
Tang, Jianting,Lv, Leiyang,Dai, Xi-Jie,Li, Chen-Chen,Li, Lu,Li, Chao-Jun
supporting information, p. 1750 - 1753 (2018/02/21)
Traditional cross-couplings require stoichiometric organometallic reagents. A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed, merging the Wolff-Kishner reduction and the classical cross-coupling reactions. Aromatic aldehydes, aryl iodides and aryl bromides are especially effective in this new cross-coupling chemistry.
Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
, p. 4622 - 4627 (2018/05/22)
A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
Zhu, Dianhu,Lv, Leiyang,Li, Chen-Chen,Ung, Sosthene,Gao, Jian,Li, Chao-Jun
supporting information, p. 16520 - 16524 (2018/11/23)
Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
Umpolung Addition of Aldehydes to Aryl Imines
Chen, Ning,Dai, Xi-Jie,Wang, Haining,Li, Chao-Jun
supporting information, p. 6260 - 6263 (2017/05/19)
One of the classical ways to synthesize amines involves the coupling of carbonyl compounds and imines, either through enolate chemistry or acyl-based carbanion equivalents. We herein report an alternative strategy that is based on the use of aldehydes as alkyl carbanion equivalents in a reductive coupling with aryl imines. A wide array of secondary amines can be synthesized in moderate to high yields. This reaction is mediated by hydrazine and catalyzed by ruthenium(II) complexes, and it tolerates various functional groups, such as esters, amides, and nitriles.
Denitrogenative hydrofluorination of aromatic aldehyde hydrazones using (difluoroiodo)toluene
Kulkarni, Kaivalya G.,Miokovic, Boris,Sauder, Matthew,Murphy, Graham K.
supporting information, p. 9907 - 9911 (2016/10/31)
An operationally simple conversion of aromatic aldehyde hydrazones to monofluoromethylated arenes is reported. The hypervalent iodine reagent TolIF2 serves as an oxidant, converting the hydrazone to the corresponding diazo compounds. The by-product of the oxidation process, HF, is consumed in situ by a denitrogenative hydrofluorination reaction of the diazo group.
