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Cationic Ru complexes anchored on POM via non-covalent interaction towards efficient transfer hydrogenation catalysis
The ionic materials consisting of cationic Ru complexes and Wells-Dawson polyoxometalate anion (POM, K6P2W18O62) have been constructed via a non-covalent interaction. The as-synthesized catalysts have been characterized thoroughly by NMR, XRD, FESEM, and FT-IR, etc. The characterization suggested that a hydrogen bond interaction occurred between the proton of the amine ligand in the cationic Ru complexes and the oxygen atom of the POM anion. The hydrogen bond played an important role in enhancing catalytic activity for the transfer hydrogenation of methyl levulinate (ML) to γ-valerolactone (GVL) under very mild conditions. Especially, the transfer hydrogenation reaction proceeded via a heterogeneous catalysis approach and the heterogenized catalysts even afforded much better catalytic performance than homogeneous analogs. Notably, the catalysts can be recycled without an obvious loss of activity, and further extended to highly selective transfer hydrogenation of α,β-unsaturated ketones and aldehydes, etc. into the corresponding α,β-unsaturated alcohols without any base external additives. The high catalytic performance of these anchored catalysts was highly related to the hydrogen bond interaction and the basicity of the polyanion. The obtained knowledge from this work could lead us to a new catalysis concept of tethering active homogeneous complexes for constructing highly active anchored Ru complex catalysts for hydrogenation reaction.
Chen, Manyu,Cui, Kai,Hou, Zhenshan,Peng, Qingpo,Wang, Jiajia,Wei, Xinjia,Zhao, Xiuge
(2021/12/22)

Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
supporting information
p. 302 - 305
(2022/01/03)

Regio- And diastereoselective Pd-catalyzed aminochlorocyclization of allylic carbamates: scope, derivatization, and mechanism
The regio- and diastereoselective synthesis of oxazolidinonesviaa Pd-catalyzed vicinal C-N/C-Cl bond-forming reaction from internal alkenes of allylic carbamates is reported. The oxazolidinones are obtained in yields of 44 to 95% with high to excellent diastereoselectivities (from 6?:?1 to >20?:?1 dr) from readily available precursors. This process is scalable, and the products are suitable for the synthesis of useful amino alcohols. A detailed theoretical and experimental mechanistic study was carried out to describe that the reaction proceeds through ananti-aminopalladation of the alkene followed by an oxidative C-Pd(ii) cleavage with retention of the carbon stereochemistry to yield the major diastereomer. The role of Cu(ii) in a C-Cl bond-forming mechanism step has also been proposed.
Ariga, Elaine Miho,Carita Correra, Thiago,Matsushima, Jullyane Emi,McIndoe, J. Scott,Moreira Ribeiro, Francisco Wanderson,Omari, Isaac,Papa Spadafora, Bruna,Rodrigues, Alessandro,Soares, Priscila Machado Arruda,Vinhato, Elisangela,de Oliveira-Silva, Diogo
supporting information
p. 5595 - 5606
(2021/07/02)

Selective, base-free hydrogenation of aldehydes catalyzed by IR complexes based on proton-responsive lutidine-derived CNP ligands
Metal catalysts based on ligands containing proton-responsive sites have found widespread applications in the hydrogenation of polar unsaturated substrates. In this contribution, Ir complexes incorporating lutidine-derived CNP (C = N-heterocyclic carbene, NHC; P = phosphine) pincer ligands with two nonequivalent Br?nsted acid/base sites have been examined in the hydrogenation of aldehydes. To this end, Ir(CNP)H2Cl complexes were synthesized in two steps from the CNP ligand precursors and Ir(acac)(COD). These derivatives react with an excess of NaH to yield the trihydride derivatives Ir(CNP)H3, which were assessed as catalyst precursors in the hydrogenation of a series of aldehydes. The catalytic reactions were performed using commercial-grade substrates under neutral, mild conditions (0.1 mol % Ir-CNP; 4 bar H2, room temperature) with high conversions and selectivities for the reduction of the carbonyl function in the presence of other readily reducible groups such as C=C, nitro, and halogens. Reaction of an Ir(CNP)H2Cl complex with base in the presence of an aromatic aldehyde produces the reversible formation of alkoxide Ir complexes in which the aldehyde is bound to the deprotonated pincer framework (CNP*) through the CH-NHC arm of the ligand. These species, along with a carboxylate complex resulting from the Ir mediated oxidation of the aldehyde by water, is observed in the reaction of Ir(CNP)H3 with benzaldehyde. Finally, investigation of the mechanism of the hydrogenation of aldehydes has been carried out by means of DFT calculations considering the involvement of each arm of the Ir-CNP/CNP* derivatives. Calculations support a mechanism in which the catalyst switches its metal?ligand cooperation sites to follow the lowest energy pathway for each step of the catalytic cycle.
álvarez, Eleuterio,Hernández-Juárez, Martín,López-Serrano, Joaquín,Paneque, Margarita,Rendón, Nuria,Sánchez, Práxedes,Suárez, Andrés
p. 1314 - 1327
(2021/05/31)

A Cationic Ru(II) Complex Intercalated into Zirconium Phosphate Layers Catalyzes Selective Hydrogenation via Heterolytic Hydrogen Activation
Catalytic hydrogenations constitute economic and clean transformations to produce pharmaceutical and a multitude of fine chemicals in chemical industry. Herein, we report a cationic Ru(II) complex intercalated into zirconium phosphate (ZrP) layers that enables the efficient catalytic conversion of furfural and other biomass-derived carbonyl compounds into the corresponding alcohols through selective hydrogenation of C=O group. The ZrP layers acted not only as a support for the Ru-complex, but also as the new ligands to tune the Ru(II) center via forming Ru?O bond. The resulting catalysts exhibit excellent catalytic performance and can be easily recycled for six times without significant loss of activity and selectivity. The Ru(II) complex-intercalated catalysts have been characterized by XRD, SEM, HRTEM, HAADF-STEM, XPS, FT-IR, DR-UV/Vis, EXAFS and XANES. Especially, it is observed that the appropriate interlayer spacing between ZrP layers is favorable to stabilize the Ru(II) complex. Notably, on the basis of the further characterization and density functional theory (DFT) calculation, it is identified that the interaction of cationic Ru(II) complex and P?OH group within ZrP layers leads to the high catalytic performance in selective hydrogenation, and the newly formed Ru?O?P species plays a crucial role in the heterolytic hydrogen activation and selective hydrogenation of biomass-derived compounds containing a carbonyl group.
Chen, Manyu,Xia, Jie,Li, Huan,Zhao, Xiuge,Peng, Qingpo,Wang, Jiajia,Gong, Honghui,Dai, Sheng,An, Pengfei,Wang, Haifeng,Hou, Zhenshan
p. 3801 - 3814
(2021/08/03)

Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
supporting information
p. 4544 - 4549
(2020/02/04)

First synthesis of 3-S-glutathionylhexanal-d8 and its bisulfite adduct
3-Sulfanylhexan-1-ol (3SH) is an impact odorant of white wines, imparting tropical fruit aromas. A reliable synthetic pathway to 3-S-glutathionylhexanal (glut-3SH-al), a precursor to 3SH that has not been intensively studied, was developed starting from 1-butanol. Application of this synthesis to 1-butanol-d10, conserved eight deuteriums, producing glut-3SH-al-d8, which can be used as an internal standard for future work on the occurrence and evolution of glut-3SH-al in wine systems. Additionally, both glut-3SH-SO3 and glut-3SH-SO3-d8 were synthesised from the corresponding aldehyde, enabling further study of the role of these bisulfite adducts in 3SH biogenesis.
Muhl, Jennifer R.,Pilkington, Lisa I.,Deed, Rebecca C.
supporting information

(2020/06/17)

Visible-Light-Promoted Intramolecular α-Allylation of Aldehydes in the Absence of Sacrificial Hydrogen Acceptors
We report herein an unprecedented protocol for radical cyclization of aldehydes with pendant alkenes via synergistic photoredox, cobaloxime, and amine catalysis. The transformation was achieved in the absence of external oxidants, providing a variety of 5-, 6-, and 7-membered ring products with alkene transposition in satisfactory yields. The reaction exhibits wide functional group compatibility and occurs under mild conditions with extrusion of H2.
Liu, Feng,Liu, Jia-Li,tu, Jia-Lin
supporting information
p. 7369 - 7372
(2020/10/05)

Copper-Catalyzed Azide–Ynamide Cyclization to Generate α-Imino Copper Carbenes: Divergent and Enantioselective Access to Polycyclic N-Heterocycles
Here an efficient copper-catalyzed cascade cyclization of azide-ynamides via α-imino copper carbene intermediates is reported, representing the first generation of α-imino copper carbenes from alkynes. This protocol enables the practical and divergent synthesis of an array of polycyclic N-heterocycles in generally good to excellent yields with broad substrate scope and excellent diastereoselectivities. Moreover, an asymmetric azide–ynamide cyclization has been achieved with high enantioselectivities (up to 98:2 e.r.) by employing BOX-Cu complexes as chiral catalysts. Thus, this protocol constitutes the first example of an asymmetric azide–alkyne cyclization. The proposed mechanistic rationale for this cascade cyclization is further supported by theoretical calculations.
Chen, Yang-Bo,Deng, Chao,Liu, Rai-Shung,Liu, Xin,Luo, Chen,Wang, Ze-Shu,Ye, Long-Wu,Zhai, Tong-Yi,Zhang, Yi-Ping
supporting information
p. 17984 - 17990
(2020/08/21)

Biosynthesis of Mycotoxin Fusaric Acid and Application of a PLP-Dependent Enzyme for Chemoenzymatic Synthesis of Substituted l -Pipecolic Acids
Fusaric acid (FA) is a well-known mycotoxin that plays an important role in plant pathology. The biosynthetic gene cluster for FA has been identified, but the biosynthetic pathway remains unclarified. Here, we elucidated the biosynthesis of FA, which features a two-enzyme catalytic cascade, a pyridoxal 5′-phosphate (PLP)-dependent enzyme (Fub7), and a flavin mononucleotide (FMN)-dependent oxidase (Fub9) in synthesizing the picolinic acid scaffold. FA biosynthesis also involves an off-line collaboration between a highly reducing polyketide synthase (HRPKS, Fub1) and a nonribosomal peptide synthetase (NRPS)-like carboxylic acid reductase (Fub8) in making an aliphatic α,β-unsaturated aldehyde. By harnessing the stereoselective C-C bond-forming activity of Fub7, we established a chemoenzymatic route for stereoconvergent synthesis of a series of 5-alkyl-, 5,5-dialkyl-, and 5,5,6-trialkyl-l-pipecolic acids of high diastereomeric ratio.
Hai, Yang,Chen, Mengbin,Huang, Arthur,Tang, Yi
supporting information
p. 19668 - 19677
(2020/12/01)

Organocatalysts Effect on the Stereoselectivity of [2,3]-Wittig Rearrangement
The organocatalytic [2,3]-Wittig rearrangement of allyloxyketones was investigated. Extensive screening of chiral amine organocatalysts showed that small pyrrolidine-based catalysts or simple phenylethylamine with the primary amino group were the most effective ones. Interestingly, CF3-derived pyrrolidine affords the rearrangement product with an opposite absolute configuration to the product obtained by using the corresponding non-fluorinated proline derived catalysts. Mechanistic and computational investigations were also performed.
Peňa?ka, Tibor,Mojzes, Melinda Meyer,Filo, Juraj,Jurdáková, Helena,Me?iarová, Mária,?ebesta, Radovan
supporting information
p. 605 - 610
(2019/01/24)

Straightforward chemo- and stereoselective fluorocyclopropanation of allylic alcohols: Exploiting the electrophilic nature of the not so elusive fluoroiodomethyllithium
An unprecedented direct fluorocyclopropanation of allylic alcohols is reported. This simple method involves the not so elusive fluoroiodomethyllithium, a carbenoidic intermediate that under the developed conditions discloses its electrophilic nature. Gratifyingly, the reaction turned out to be highly chemo- and stereoselective, and DFT calculations provided insights into the structure and nature of this new type of carbenoid.
Colella, Marco,Tota, Arianna,Gro?johann, Angela,Carlucci, Claudia,Aramini, Andrea,Sheikh, Nadeem S.,Degennaro, Leonardo,Luisi, Renzo
supporting information
p. 8430 - 8433
(2019/07/22)

Hafnium Triflate as a Highly Potent Catalyst for Regio- and Chemoselective Deprotection of Silyl Ethers
As a Group IVB transition metal Lewis acid, hafnium triflate [Hf(OTf) 4 ] exhibited exceptionally high potency in desilylations. Since the amounts of Hf(OTf) 4 required for the deprotection of 1°, 2°, 3° alkyl and aryl tert -butyldimethylsilyl (TBS) ethers are significantly different, ranging from 0.05 mol% to 3 mol%, regioselective deprotection of TBS could be easily implemented. Moreover, chemoselective cleavage of different silyl ethers or removal of TBS in the presence of most hydroxyl protecting groups was also accomplished. NMR analyses of silyl products from TBS deprotection indicated that Hf(OTf) 4 -catalyzed desilylation may proceed via different mechanisms, depending on the solvent used.
Zheng, Xiu-An,Kong, Rui,Huang, Hua-Shan,Wei, Jing-Ying,Chen, Ji-Zong,Gong, Shan-Shan,Sun, Qi
supporting information
p. 944 - 953
(2019/02/10)

Three-Dimensionally Hierarchical Pt/C Nanocomposite with Ultra-High Dispersion of Pt Nanoparticles as a Highly Efficient Catalyst for Chemoselective Cinnamaldehyde Hydrogenation
A monolithic carbon-supported Pt nanocomposite with an interconnected three-dimensionally hierarchical porous carbon framework and ultra-high dispersion of Pt nanoparticles (Pt/3DHPC) is synthesized by using an effective “liquid phase impregnation template” strategy. The obtained Pt/3DHPC possesses rich mesoporosity and a low amount of oxygen-containing functional groups, which notably improve the accessible internal surface area of macropores, number of active Pt sites, and electron transfer ability. When used as a catalyst for the selective cinnamaldehyde (CMA) hydrogenation towards cinnamyl alcohol (CMO), Pt/3DHPC exhibits high CMA conversion (92.7 %) and CMO selectivity (91.1 %) at 1 h reaction time, and the corresponding activity (1553.7 h?1) greatly surpasses not only the single-sized mesoporous carbon and microporous activated carbon-supported counterparts but also the previously reported Pt catalysts dispersed on other forms of carbon. Furthermore, Pt/3DHPC can be reused at least fifteen times without pronounced decay owing to the strong interaction between Pt and carbon. The present work demonstrates the validity of multiscale control in carbon-supported Pt catalysts by overall consideration of the mass transportation, and the accessibility, quantity, and capability of active sites towards chemoselective hydrogenation of CMA, which is expected to be extended to other catalysis-related processes.
Hu, Duo,Fan, Wenqian,Liu, Zhi,Li, Ling
p. 779 - 788
(2018/01/04)

Efficient Pd-Catalyzed Regio- and Stereoselective Carboxylation of Allylic Alcohols with Formic Acid
Formic acid is efficiently used as a C1 source to directly carboxylate allylic alcohols in the presence of a low loading of palladium catalyst and acetic anhydride as additive to afford β,γ-unsaturated carboxylic acids with excellent chemo-, regio-, and stereoselectivity. The reaction proceeds through a carbonylation process with in situ-generated carbon monoxide under mild conditions, avoiding the use of high-pressure gaseous CO. A bisphosphine ligand with a large bite angle (4,5-bis{diphenylphosphino}-9,9-dimethylxanthene, Xantphos) was found to be uniquely effective for this transformation. The regio- and stereoconvergence of this reaction is ascribed to the thermodynamically favored isomerization of the allylic electrophile in the presence of the palladium catalyst.
Fu, Ming-Chen,Shang, Rui,Cheng, Wan-Min,Fu, Yao
supporting information
p. 8818 - 8822
(2017/07/11)

Identification of (Z)-3:(E)-2-Hexenal isomerases essential to the production of the leaf aldehyde in plants
The green odor of plants is characterized by green leaf volatiles (GLVs) composed of C6 compounds. GLVs are biosynthesized from polyunsaturated fatty acids in thylakoid membranes by a series of enzymes. A representative member of GLVs (E)-2-hexenal, known as the leaf aldehyde, has been assumed to be produced by isomerization from (Z)-3-hexenal in the biosynthesis pathway; however, the enzyme has not yet been identified. In this study, we purified the (Z)-3:(E)-2-hexenal isomerase (HI) from paprika fruits and showed that various plant species have homologous HIs. Purified HI is a homotrimeric protein of 110 kDa composed of 35-kDa subunits and shows high activity at acidic and neutral pH values. Phylogenetic analysis showed that HIs belong to the cupin superfamily, and at least three catalytic amino acids (His, Lys, Tyr) are conserved in HIs of various plant species. Enzymatic isomerization of (Z)-3-hexenal in the presence of deuterium oxide resulted in the introduction of deuterium at the C4 position of (E)-2-hexenal, and a suicide substrate 3-hexyn-1-al inhibited HI irreversibly, suggesting that the catalytic mode of HI is a keto-enol tautomerism reaction mode mediated by a catalytic His residue. The gene expression of HIs in Solanaceae plants was enhanced in specific developmental stages and by wounding treatment. Transgenic tomato plants overexpressing paprika HI accumulated (E)-2-hexenal in contrast to wild-type tomato plants mainly accumulating (Z)-3-hexenal, suggesting that HI plays a key role in the production of (E)-2-hexenal in planta.
Kunishima, Mikiko,Yamauchi, Yasuo,Mizutani, Masaharu,Kuse, Masaki,Takikawa, Hirosato,Sugimoto, Yukihiro
p. 14023 - 14033
(2016/07/11)

Electronic interactions between a stable electride and a nano-alloy control the chemoselective reduction reaction
Controlling the electronic structure of heterogeneous metal catalysts is considered an efficient method to optimize catalytic activity. Here, we introduce a new electronic effect induced by the synergy of a stable electride and bimetallic nanoparticles for a chemoselective reduction reaction. The electride [Ca24Al28O64]4+·(e-)4, with extremely low work function, promotes the superior activity and selectivity of a Ru-Fe nano-alloy for the conversion of α,β-unsaturated aldehydes to unsaturated alcohols in a solvent-free system. The catalyst is easily separable from the product solution and reusable without notable deactivation. Mechanistic studies demonstrate that electron injection from the electride to the Ru-Fe bimetallic nanoparticles promotes H2 dissociation on the highly charged active metal and preferential adsorption of CO bonds over CCs bond of the unsaturated aldehydes, to obtain the thermodynamically unfavorable but industrially important product.
Ye, Tian-Nan,Li, Jiang,Kitano, Masaaki,Sasase, Masato,Hosono, Hideo
p. 5969 - 5975
(2016/08/31)

Chemoselective transfer hydrogenation of α,β-unsaturated carbonyl compounds using potassium formate over amine-grafted Ru/AlO(OH) catalysts
Grafting of 3-(2-aminoethylamino)propyltrimethoxysilane onto Ru/AlO(OH) resulted in an active and highly chemoselective heterogeneous catalyst for the transfer hydrogenation of α,β-unsaturated carbonyl compounds to the corresponding allylic alcohols. Potassium formate was used as a sustainable hydrogen donor. A range of substrates including cinnamaldehyde, α-amylcinnamaldehyde, citral, 3-methyl-2-butenal, trans-2-pentenal, and trans-hexenal were selectively hydrogenated at the CO moiety with >96% selectivity. In comparison, the unmodified 1 wt% Ru/AlO(OH) catalyzed hydrogenation of cinnamaldehyde at the CC bond, yielding 3-phenylpropanal as the product. Higher loaded samples with 2-10 wt% Ru exhibited 20-25% selectivity to cinnamyl alcohol. The results show that low coordination sites were more selective to hydrogenation of the internal CC than the terminal CO bond. Immobilization of the amine via chemical bonding with hydroxyl groups of the AlO(OH) support blocks adjacent exposed metal sites, increasing the chemoselective reduction of CO. Optimum results were achieved at an amine/Ru ratio of 6. The catalyst maintained high activity and chemoselectivity even after five cycles.
Gao, Yanxiu,Wang, Jie,Han, Aijuan,Jaenicke, Stephan,Chuah, Gaik Khuan
p. 3806 - 3813
(2016/06/13)

Selective Pinacol-Coupling Reaction using a Continuous Flow System
The first continuous flow pinacol coupling reaction of carbonyl compounds was successfully achieved within only 2 min during a single pass through a cartridge filled with zinc(0). The optimized method allowed the efficient production of gram-scale value-added compounds with high productivity. The developed methodology is efficient for aromatic or α,β-unsaturated aldehydes but gives moderate results for more stable acetophenone derivatives. Moreover, the flow method displayed better results in terms of yield and selectivity in comparison to the corresponding batch methodology.
Sotto, Nicolas,Cazorla, Clément,Villette, Carole,Billamboz, Muriel,Len, Christophe
p. 11065 - 11071
(2016/11/28)

Air-Stable Gold Nanoparticles Ligated by Secondary Phosphine Oxides as Catalyst for the Chemoselective Hydrogenation of Substituted Aldehydes: A Remarkable Ligand Effect
Air-stable and homogeneous gold nanoparticles (AuNPs, 1a-5a) ligated by various secondary phosphine oxides (SPOs), [R1R2P(O)H] (R1 = Naph, R2 = tBu, L1; R1 = R2 = Ph, L2; R1 = Ph, R2 = Naph, L3; R1 = R2 = Et, L4; R1 = R2 = Cy, L5; R1 = R2 = tBu, L6), with different electronic and steric properties were synthesized via NaBH4 reduction of the corresponding Au(I)-SPO complex. These easily accessible ligands allow the formation of well dispersed and small nanoparticles (size 1.2-2.2 nm), which were characterized by the use of a wide variety of techniques, such as transmission electron microscopy, thermogravimetric analysis, UV-vis, energy-dispersive X-ray, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), and cross polarization magic angle spinning (CP MAS) NMR spectroscopy. A pronounced ligand effect was found, and CP MAS NMR experiments enabled us to probe important differences in the polarity of the P-O bond of the SPOs coordinated to the nanoparticle surface depending on the type of substituents in the ligand. AuNPs containing aryl SPOs carry only SPO anions and are highly selective for aldehyde hydrogenation. AuNPs of similar size made with alkyl SPOs contain also SPOH, hydrogen bonded to SPO anions. As a consequence they contain less Au(I) and more Au(0), as is also evidenced by XPS. They are less selective and active in aldehyde hydrogenation and now show the typical activity of Au(0)NPs in nitro group hydrogenation. (Chemical Equation Presented).
Cano, Israel,Huertos, Miguel A.,Chapman, Andrew M.,Buntkowsky, Gerd,Gutmann, Torsten,Groszewicz, Pedro B.,Van Leeuwen, Piet W. N. M.
supporting information
p. 7718 - 7727
(2015/07/01)

Simple and expeditious pinacol coupling of non usual α,β-unsaturated carbonyl compounds in water
Using zinc (0) in a 5% v AcOH aqueous solution allowed the efficient pinacol coupling of aliphatic or aromatic unusual, α,β-unsaturated carbonyl compounds such as citral A in good to excellent yields (56-99%). It can also be successfully applied to acetophenone.
Billamboz, Muriel,Sotto, Nicolas,Chevrin-Villette, Carole,Len, Christophe
p. 46026 - 46030
(2015/06/08)

Selective Pinacol Coupling on Regeneratable Supported Acids in Sole Water
Efficient pinacol coupling was developed in sole water, using a reusable heterogeneous supported acid source and zinc as cheap available metal source. This medium can be easily regenerated up to 10-fold without loss of activity. Moreover, supported acids enhance the selectivity of the pinacol coupling reaction compared with homogeneous acids.
Sotto, Nicolas,Billamboz, Muriel,Chevrin-Villette, Carole,Len, Christophe
p. 6375 - 6380
(2015/06/30)

Eco-friendly stereoselective reduction of α,β-unsaturated carbonyl compounds by Er(OTf)3/NaBH4 in 2-MeTHF
An operationally simple and environmentally benign catalytic procedure has been developed to selectively reduce different α,β-unsaturated ketones. The corresponding allylic alcohols are obtained with high chemo- and diastereoselectivity using Er(OTf)3 and NaBH4 in 2-MeTHF. This protocol reduces the amount of catalyst and NaBH4 needed, compared to classical procedures and the stages of extraction/purification are carried out in aqueous solutions avoiding the use of toxic solvents. Taking into account that Er(OTf)3 can be considered even less toxic than table salt and the 'greenness' of 2-MeTHF as a solvent, the system Er(OTf)3/2-MeTHF can be proposed as a cheap, efficient, and environmentally sustainable reduction system for the synthesis of allylic alcohols.
Nardi, Monica,Sindona, Giovanni,Costanzo, Paola,Oliverio, Manuela,Procopio, Antonio
p. 1132 - 1135
(2015/02/19)

Identification of a marine NADPH-dependent aldehyde reductase for chemoselective reduction of aldehydes
A putative aldehyde reductase gene from Oceanospirillum sp. MED92 was overexpressed in Escherichia coli. The recombinant protein (OsAR) was characterized as a monomeric NADPH-dependent aldehyde reductase. The kinetic parameters Km and kcat of OsAR were 0.89 ± 0.08 mM and 11.07 ± 0.99 s-1 for benzaldehyde, 0.04 ± 0.01 mM and 6.05 ± 1.56 s-1 for NADPH, respectively. This enzyme exhibited high activity toward a variety of aromatic and aliphatic aldehydes, but no activity toward ketones. As such, it catalyzed the chemoselective reduction of aldehydes in the presence of ketones, as demonstrated by the reduction of 4-acetylbenzaldehyde or the mixture of hexanal and 2-nonanone, showing the application potential of this marine enzyme in such selective reduction of synthetic importance.
Li, Guangyue,Ren, Jie,Wu, Qiaqing,Feng, Jinhui,Zhu, Dunming,Ma, Yanhe
p. 17 - 22
(2013/05/08)

Asymmetric allylic alkylation of acyclic allylic ethers with organolithium reagents
A highly efficient, regio- and enantioselective CuI/ phosphoramidite-catalyzed asymmetric allylic alkylation of allyl ethers with organolithium reagents is reported (see scheme). The use of organolithium reagents is essential for this catalytic C-C bond formation due to their compatibility with different Lewis acids. The versatility of allylic ethers under the copper-catalyzed reaction conditions with organolithium reagents is demonstrated in the shortest synthesis of (S)-Arundic acid. Copyright
Pérez, Manuel,Fa?anás-Mastral, Martín,Hornillos, Valentín,Rudolph, Alena,Bos, Pieter H.,Harutyunyan, Syuzanna R.,Feringa, Ben L.
supporting information
p. 11880 - 11883
(2012/10/29)

A novel preparation method of nisn alloy catalysts supported on aluminium hydroxide: Application to chemoselective hydrogenation of unsaturated carbonyl compounds
A novel method was applied for the preparation of NiSn alloy catalysts that were utilized for chemoselective hydrogenation of unsaturated carbonyl compounds, producing unsaturated alcohols almost exclusively. The formation of the NiSn alloy may have played a key role in the enhancement of the chemoselectivity.
Rodiansono,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
supporting information; experimental part
p. 769 - 771
(2012/09/21)

Highly efficient and stereoselective biosynthesis of (2S,5S)-hexanediol with a dehydrogenase from Saccharomyces cerevisiae
The enantiopure (2S,5S)-hexanediol serves as a versatile building block for the production of various fine chemicals and pharmaceuticals. For industrial and commercial scale, the diol is currently obtained through bakers' yeast-mediated reduction of 2,5-hexanedione. However, this process suffers from its insufficient space-time yield of about 4 g L-1 d-1 (2S,5S)-hexanediol. Thus, a new synthesis route is required that allows for higher volumetric productivity. For this reason, the enzyme which is responsible for 2,5-hexanedione reduction in bakers' yeast was identified after purification to homogeneity and subsequent MALDI-TOF mass spectroscopy analysis. As a result, the dehydrogenase Gre2p was shown to be responsible for the majority of the diketone reduction, by comparison to a Gre2p deletion strain lacking activity towards 2,5-hexanedione. Bioreduction using the recombinant enzyme afforded the (2S,5S)-hexanediol with >99% conversion yield and in >99.9% de and ee. Moreover, the diol was obtained with an unsurpassed high volumetric productivity of 70 g L-1 d-1 (2S,5S)-hexanediol. Michaelis-Menten kinetic studies have shown that Gre2p is capable of catalysing both the reduction of 2,5-hexanedione as well as the oxidation of (2S,5S)-hexanediol, but the catalytic efficiency of the reduction is three times higher. Furthermore, the enzyme's ability to reduce other keto-compounds, including further diketones, was studied, revealing that the application can be extended to α-diketones and aldehydes.
Mueller, Marion,Katzberg, Michael,Bertau, Martin,Hummel, Werner
experimental part
p. 1540 - 1550
(2010/07/04)

Chemo-enzymatic asymmetric total synthesis of penienone
An asymmetric synthesis of penienone has been accomplished from (R)-5-hydroxymethyl-2-cyclohexenone by adopting a linear strategy. Lipase-PS-catalyzed enzymatic kinetic resolution (EKR) and Julia-Kocienski olefination followed by substrate-directed anioni
Mahapatra, Tridib,Bhunya, Rajib,Nanda, Samik
body text
p. 5392 - 5394
(2009/12/06)

First stereoselective total synthesis and anticancer activity of new amide alkaloids of roots of pepper
The first stereoselective total synthesis of new natural amide alkaloids 1-3 have been achieved from commercially available starting materials. Wittig olefination, Sharpless asymmetric dihydroxylation, epoxidation, a trans regioselective opening of 2,3-epoxy alcohol, Horner-Wadsworth-Emmons (HWE) olefination and amide coupling are the key steps. The amide alkaloids 1-3 are evaluated for their anticancer activity against colon (HT-29), breast (MCF-7) and lung (A-549) human cancer cell lines for the first time.
Srinivas,Sai Pavan Kumar,China Raju,Jayathirtha Rao,Naidu,Ramakrishna,Diwan, Prakash V.
scheme or table
p. 5915 - 5918
(2010/04/29)

Enantiocontrolled synthesis of polychlorinated hydrocarbon motifs: A nucleophilic multiple chlorination process revisited
Polychlorinated hydrocarbon motifs have been synthesized in enantiomerically pure forms by means of nucleophilic multiple chlorinations of chiral epoxides, which stereospecifically incorporate halogen atoms into oxygenated molecular scaffolds. The present
Yoshimitsu, Takehiko,Fukumoto, Naoya,Tanaka, Tetsuaki
supporting information; experimental part
p. 696 - 702
(2009/06/28)

Direct reductive amination and selective 1,2-reduction of α,β-unsaturated aldehydes and ketones by NaBH4 using H3PW12O40 as catalyst
A simple and convenient procedure for direct reductive amination of aldehydes and ketones with sodium borohydride is described. The reaction has been carried out in methanol in the presence of a catalytic amount of H3PW12O40 (0.5 mol %). α,β-Unsaturated aldehydes and ketones can be easily converted into the corresponding allyl alcohols by reaction with H3PW12O40 (0.5 mol %)/NaBH4.
Heydari, Akbar,Khaksar, Samad,Akbari, Jafar,Esfandyari, Maryam,Pourayoubi, Mehrdad,Tajbakhsh, Mahmoud
p. 1135 - 1138
(2007/10/03)

Highly selective methanesulfonic acid-catalyzed 1,3-isomerization of allylic alcohols
Secondary and tertiary allylic alcohols undergo 1,3-isomerization smoothly in the presence of methanesulfonic acid under simple and efficient conditions to afford selectively the corresponding primary E-allylic alcohols in excellent yields.
Leleti, Rajender Reddy,Hu, Bin,Prashad, Mahavir,Repi?, Oljan
p. 8505 - 8507
(2008/09/16)

Efficient and stereoselective synthesis of allylic ethers and alcohols
(Chemical Equation Presented) A short and efficient synthesis of allylic TBS ethers and allylic alcohols has been developed, based upon a unique Kocienski-Julia olefination reaction. Allylic alcohols and allylic ethers are obtained in good to excellent yields and with high (E)-selectivity. The conditions are mild and the procedure is broadly applicable.
Pospisil, Jiri,Marko, Istvan E.
p. 5983 - 5986
(2007/10/03)

A facile, catalytic, and environmentally benign method for selective deprotection of teri-butyldimethylsilyl ether mediated by phosphomolybdic acid supported on silica gel
An environmentally benign PMA supported on SiO2 is found to be an efficient catalyst for the chemoselective deprotection of TBDMS ethers under very mild conditions. Various labile functional groups such as isopropylidene acetal, OTBDPS, OTHP, Oallyl, OBn, alkene, alkyne, OAc, OBz, N-Boc, N-Cbz, N-Fmoc, mesylate, and azide are found to be stable under the reaction conditions. This "truly catalytic" heterogeneous reaction does not require aqueous workup, and the supported catalyst and the solvent can be readily recovered and recycled.
Kishore Kumar,Baskaran, Sundarababu
p. 4520 - 4523
(2007/10/03)

Asymmetric rearrangement of allylic trichloroacetimidates: Preparation of (s)-2,2,2trichloro-n-(1-propylallyl)acetamide (acetamide, 2,2,2-trichloro-N-[(1S)-1-ethenylbutyl]-)
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Anderson, Carolyn E.,Overman, Larry E.,Watson, Mary P.,Maddess, Matthew L.,Lautens, Mark
p. 134 - 139
(2017/09/25)

Catalytic Regiodivergent Kinetic Resolution of Allylic Epoxides: A New Entry to Allylic and Homoallylic Alcohols with High Optical Purity
A novel regiodivergent kinetic resolution of a series of allylic epoxides with alkylzinc reagents is described. Results demonstrate the potential of chiral copper-phosphoramidite catalysts for enantiomer differentiation of allylic epoxides, allowing a chiral catalyst-stereoregulated synthesis of cyclic allylic and homoallylic alcohols with high optical purities.
Pineschi, Mauro,Del Moro, Federica,Crotti, Paolo,Di Bussolo, Valeria,Macchia, Franco
p. 2099 - 2105
(2007/10/03)

In situ 1H-PHIP-NMR studies of the stereoselective hydrogenation of alkynes to (E)-alkenes catalyzed by a homogeneous [Cp*Ru]+ catalyst
The hydrogenation of internal alkynes using a [Cp*Ru(alkene)]+ complex leads to the formation of (E)-alkenes. This ruthenium complex represents one of the few homogeneous catalysts that trans-hydrogenate internal alkynes directly and stereoselectively. We have studied its stereoselectivity by in situ PHIP-NMR spectroscopy (PHIP = para-hydrogen induced polarization). With this method the initially formed products can be identified and characterized even at very low concentrations and low conversions. Furthermore, their subsequent fate can be evaluated with high sensitivity and with time resolution. Different alkyne substrates were used to demonstrate the universal applicability of this catalyst. The catalyst is not active in combination with terminal alkynes, however, possibly due to the formation of a rather stable vinylidene complex. A mechanism proceeding via a binuclear complex is proposed to explain the formation of the (E)-alkenes.
Schleyer,Niessen,Bargon
p. 423 - 426
(2007/10/03)

Catalysts containing zirconium oxide
Catalyst compositions based on amorphous partially dehydrated zirconium hydroxide which are doped with from 0.01 to 20 atom percent of copper and/or from 0.01 to 20 atom percent of nickel, in each case based on zirconium, and have a specific surface area by the BET method of at least 50 m2/g. The catalyst compositions are suitable, in particular, as the catalyst in hydrogen transfer reactions, such as, the Meerwein-Ponndorf-Verley reduction or the Oppenauer oxidation. The preparation of 3-hydroxyquinuclidine of the formula: involves reaction of quinuclidin-3-one with a secondary alcohol in the presence of the amorphous partially dehydrated zirconium hydroxide.
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(2008/06/13)

Synthesis of the sex pheromone of Lygus lineolaris (Heteroptera miridae)
We propose a new synthesis of the sex pheromone of Lygus lineolaris (Heteroptera miridae) that uses a phase-transfer version of the Wittig - Horner reaction to produce a monoene synthon of the principal component of the pheromone, E-2-hexenylbutyrate.
Shakirzyanova,Abdukakharov,Abduvakhabov
p. 623 - 624
(2007/10/03)

Convenient one pot conversion of acetals into alcohols
Various acetals are conveniently converted into alcohols using a one pot procedure that combines hydrolysis of an acetal by triflouromethanesulfonic acid in tetrahydrofuran and tert-butylamine borane reduction of the resulting aldehyde.
Lukin, Kirill A.,Yang, ChengXi,Bellettini, John R.,Narayanan,Leanna, M. Robert,Rasmussen, Michael
p. 59 - 60
(2007/10/03)

Selective reduction of carbonyl compounds by polymethylhydrosiloxane in the presence of metal hydride catalysts
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Mimoun
p. 2582 - 2589
(2007/10/03)

Stereoselective routes to E and Z straight-chain primary allylic amines
Stereoselective reduction of a triple C-C bond and chemoselective transformation of an azide function into amino group have been employed in the synthesis of straight-chain primary E and Z allylic amines from alk-2- yn-1-ols.
Tomassy, Beata,Zwierzak, Andrzej
p. 1201 - 1214
(2007/10/03)

Modofied Borohydride Agents, (1,4-Diazabicyclooctane)(tetrahydroboronato)zinc Complex . A New Ligand Metal Borohydride as a Stable, Efficient, and Versatile Reducing Agent
(1,4-Diazabicyclooctane)(tetrahydroborato)zinc complex is a stable compound which has been used for the selective reduction of aldehydes, ketones, α,β-unsaturated carbonyl compounds, α-diketones, acyloins and acyl chlorides to their alcohols and aldehydes in THF or CH2Cl2/hexane at room temperature or under reflux conditions.
Firouzabadi, Habib,Zeynizadeh, Behzad
p. 156 - 168
(2007/10/03)

Mechanistic Insights into the Very Efficient [ReO3OSiR3]-Catalyzed Isomerization of Allyl Alcohols
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Bellemin-Laponnaz, Stephane,Gisie, Herve,Le Ny, Jean Pierre,Osborn, John A.
p. 976 - 978
(2007/10/03)

Concomitant Epoxide Deoxygenation and Deacetylation of Glycidyl Acetates Induced by Telluride Ion
Treatment of glycidyl acetates with telluride ion (Te(2-)) produced by reduction of elemental Te with LiEt3BH yields allylic alcohols by loss of the epoxide oxygen atom and the acetyl group from the ester.If the glycidyl acetate is disubstituted at C-3, a rearrangement to an isomeric allylic alcohol competes with the deoxygenation-deacetylation.Triethylborane, a byproduct in the reduction of Te, is believed to play an important role as a Lewis acid since when it is absent or removed by addition of fluoride ion the reaction is extremely slow.
Dittmer, Donald C.,Zhang, Yanzhi,Discordia, Robert P.
p. 1004 - 1010
(2007/10/02)

COMPOUNDS WITH A HERBAL ODOR VI. THE E ISOMERS OF THE STRUCTURAL ANALOGS OF LEAF ALCOHOL
The E isomers of leaf alcohol and its structural analogs differing in the length of the carbon chain, the presence of substituents at various positions of the molecule, the position of the double bond, and replacement of the double bond by a three-membered ring were synthesized.Many representatives of the Z and E series have a herbal odor, and similarity is observed in the odor of the respective pairs of Z and E isomers.The proximity of the odor of the investigated compounds to the standard (leaf alcohol) is determined by the number of carbon atoms in their molecules.
Vasil'ev, A. A.,Cherkaev, G. V.,Nikitina, M. A.
p. 870 - 875
(2007/10/02)

The Catalytic Reduction of Aldehydes and Ketones with 2-Propanol over Silica-Supported Zirconium Catalyst
Reduction of aldehydes and ketones with 2-propanol proceeded efficiently over silica-supported zirconium catalyst, and the correspondimg alcohols were obtained in high yields.In the reduction of aldehyde, the acetalization did not occur and the side reaction, the aldol condensation, was inhibited.
Inada, Kazushige,Shibagaki, Makoto,Nakanishi, Yukio,Matsushita, Hajime
p. 1795 - 1798
(2007/10/02)

Chemoselective reductions with sodium borohydride
Under the appropriate reaction conditions, sodium borohydride is a highly chemoselective reducing agent.The order of reactivity among carbonyl groups is conjugated enonesketonesconjugated aldehydesaldehydes.In general, a carbonyl group of one type can be selectively reduced in the presence of a carbonyl group of a less reactive type.Reactions are conducted with excess sodium borohydride at -78 deg C in solvent mixtures of methanol or ethanol in dichloromethane.Key words: sodium borohydride, chemoselective reductions.
Ward, Dale E.,Rhee, Chung K.
p. 1206 - 1211
(2007/10/02)

NICKEL(II)-CATALYZED ALKYLATION OF 2-METHYL-1,3-DIOXEP-4-ENE BY GRIGNARD REAGENTS: AN EFFICIENT AND SELECTIVE ROUTE TO ALLYLIC ALCOHOLS
Allylic alcohols are formed, in good yields, through the regiocontrolled Cl2Nidppe-catalyzed alkylation of 2-methyl-1,3-dioxep-4-ene by Grignard reagents .Highly pure Z alcohols arise when secondary and tertiary aliphatic Grignards are used.
Menicagli, Rita,Malanga, Corrado,Finato, Barbara,Lardicci, Luciano
p. 69 - 70
(2007/10/02)

Meerwein-Ponndorf-Verley-Type Reduction of Dicarbonyl Compounds to Hydroxy Carbonyl Compounds and α,β-Unsaturated Carbonyl Compounds to Allylic Alcohols Catalyzed by Zirconocene and Hafnocene Complexes
Group IVA metallocene complexes such as bis(η5-cyclopentadienyl)zirconium dihydrides, Cp2ZrH2 (1), and hafnium dihydrides, Cp2HfH2 (8), catalyze the chemoselective reduction of polycarbonyl compounds to hydroxy carbonyl compounds.For instance, the reduction of keto aldehydes 3-ketobutanal (2g) and 2-phenyl-2-ketoethanal (2h) proceeded selectively at aldehyde group to provide the corresponding hydroxy ketones 3g and 3h in 91percent and 93percent yields, respectively.Under similar conditions, however, cyclohexanediones were easily aromatized to benzenediols.On the other hand, 1 and 8 also catalyze the selective 1,2-reduction of various types of α,β-unsaturated carbonyl compounds, giving the corresponding allylic alcohols in good to excellent yields.Thus, steroidal dicarbonyl compounds, having an enone framework in their molecules Δ4-androstene-3,17-dione (11a) and Δ4-progestene-3,20-dione (11b) were reduced by 1 to 17-hydroxy-Δ4-androsten-3-one (12a) and 20-hydroxy-Δ4-progest-3-one (12b), which are essential human hormones, in 80percent and 67percent yields, respectively.
Nakano, Tatsuya,Umano, Shigetoshi,Kino, Yoshio,Ishii, Yasutaka,Ogawa, Masaya
p. 3752 - 3757
(2007/10/02)