90392-95-3Relevant academic research and scientific papers
Enantioselective Redox-Neutral Coupling of Aldehydes and Alkenes by an Iron-Catalyzed "catch-Release" Tethering Approach
Li, Jing,Preinfalk, Alexander,Maulide, Nuno
, p. 143 - 147 (2019)
The reductive coupling of aldehydes and alkenes is an emerging technology that holds the potential to reinvent carbonyl addition chemistry. However, existing enantioselective methods are limited to form "branched" products. Herein, we present a directed enantio- and diastereoselective alkylation of aldehydes with simple olefins to selectively yield linear coupling products. This is achieved by redox-neutral remote functionalization, whereby a tethering "catch-release" strategy decisively solves the key problems of reactivity and selectivity.
Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey–Seebach Reaction
Crespi, Stefano,Donabauer, Karsten,K?nig, Burkhard,Murugesan, Kathiravan,Rozman, Ur?a
supporting information, p. 12945 - 12950 (2020/09/23)
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C?H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
Chemoselective Nucleophilic Functionalizations of Aromatic Aldehydes and Acetals via Pyridinium Salt Intermediates
Kawajiri, Takahiro,Kato, Maho,Nakata, Hiroki,Goto, Ryota,Aibara, Shin-Yo,Ohta, Reiya,Fujioka, Hiromichi,Sajiki, Hironao,Sawama, Yoshinari
, p. 3853 - 3870 (2019/03/07)
The development of a novel chemoselective functionalization can diversify the strategy for synthesizing the target molecules. The perfect chemoselectivity between aromatic and aliphatic aldehydes is difficult to achieve by the previous methods. The aromatic aldehyde-selective nucleophilic addition in the presence of aliphatic aldehydes was newly accomplished. Namely, the aromatic aldehyde-selective nucleophilic addition using arenes and allyl silanes proceeded in the presence of trialkylsilyl triflate and 2,2′-bipyridyl, while the aliphatic aldehydes completely remained unchanged. The reactive pyridinium-type salt intermediate derived from an aromatic aldehyde chemoselectively underwent the nucleophilic substitution. Moreover, the aromatic acetals as the protected aldehydes could be directly transformed into similar pyridinium salt intermediates, which reacted with various nucleophiles coexisting with the aliphatic aldehydes.
Cyclopentadienyl Ruthenium(II) Complex-Mediated Oxidation of Benzylic and Allylic Alcohols to Corresponding Aldehydes
Chern, Ching-Yuh,Tseng, Ching-Chun,Hsiao, Rong-Hong,Wong, Fung Fuh,Kuo, Yueh-Hsiung
, (2019/09/13)
This work reports an efficient method for the oxidation reaction of aliphatic, aromatic allylic, and benzylic alcohols into aldehydes catalyzed by the cyclopentadienyl ruthenium(II) complex (RuCpCl(PPh3)2) with bubbled O2. Through further optimizing controlled studies, the tendency order of oxidation reactivity was determined as follows: benzylic alcohols > aromatic allylic alcohols >> aliphatic alcohols. In addition, this method has several advantages, including a small amount of catalyst (0.5 mol%) and selective application of high discrimination activity of aliphatic, aromatic allylic, and benzylic alcohols.
Aromatic aldehyde-selective aldol addition with aldehyde-derived silyl enol ethers
Kawajiri, Takahiro,Ohta, Reiya,Fujioka, Hiromichi,Sajiki, Hironao,Sawama, Yoshinari
supporting information, p. 374 - 377 (2018/02/27)
The aldol reaction using aldehyde-derived silyl enolates as nucleophiles with aromatic aldehydes chemoselectively proceeded in the presence of silyl triflate and 2,2′-bipyridyl to produce β-siloxy aldehydes, while the aliphatic aldehydes were completely recovered. The unprecedented chemoselectivities depend on the reactivities of the pyridinium-type intermediates derived from the aromatic and aliphatic aldehydes.
Palladium on Carbon-Catalyzed Chemoselective Oxygen Oxidation of Aromatic Acetals
Yasukawa, Naoki,Asai, Shota,Kato, Maho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
, p. 5604 - 5607 (2016/11/17)
The development of an unprecedented chemoselective transformation has contributed to forming a novel synthetic process for target molecules. Chemoselective oxidation of aromatic acetals has been accomplished using a reusable palladium on carbon catalyst under atmospheric oxygen conditions to form ester derivatives with tolerance of aliphatic acetals and ketals.
Synthetic utility of iodic acid in the oxidation of benzylic alcohols to aromatic aldehydes and ketones
Imai, Sho,Togo, Hideo
, p. 6948 - 6954 (2016/10/13)
Various primary and secondary benzylic alcohols were efficiently oxidized to aromatic aldehydes and aromatic ketones with iodic acid in DMF at 60?°C for 2?h and with iodic acid in the presence of TEMPO (5?mol?%) in DMF at room temperature, respectively. The former method was effective for the oxidation of sterically hindered alcohols at 60?°C and the latter method was effective for the oxidation of less sterically hindered alcohols at room temperature.
Fluorous bispidine: A bifunctional reagent for copper-catalyzed oxidation and knoevenagel condensation reactions in water
Ang, Wei Jie,Chng, Yong Sheng,Lam, Yulin
, p. 81415 - 81428 (2015/10/06)
Fluorous bispidine-type ligands have been developed to facilitate its recovery and reusability and to demonstrate its bifunctional property as a ligand and base in copper-catalyzed aerobic oxidation, the Knoevenagel condensation and tandem oxidation/Knoevenagel condensation in water under mild conditions. Application of the fluorous ligand was also extended to the surfactant-free copper-catalyzed allylic and benzylic sp3 C-H oxidation reaction in water. The fluorous ligands could be recovered using F-SPE with recovery ranging from 91-97% and could be reused five times with little loss of activity.
NMO·TPB: A selectivity variation on the Ley-Griffith TPAP oxidation
Moore, Peter W.,Mirzayans, Paul M.,Williams, Craig M.
supporting information, p. 3567 - 3571 (2015/03/04)
A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO·TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.
Selective oxidations of activated alcohols in water at room temperature
Lipshutz,Hageman,Fennewald,Linstadt,Slack,Voigtritter
, p. 11378 - 11381 (2014/11/08)
Allylic and benzylic alcohols can be selectively oxidized to their corresponding aldehydes or ketones in water containing nanoreactors composed of the designer surfactant TPGS-750-M. The oxidation relies on catalytic amounts of CuBr, bpy, and TEMPO, with N-methyl-imidazole; air is the stoichiometric oxidant. the Partner Organisations 2014.
