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Volume 2, Issue 11
Article first published online: 12 NOV 2013 | DOI: 10.1002/ajoc.201390030
The Mukaiyama aldol reaction is 40 years old this year. In this special issue we celebrate Professor Mukaiyama's seminal discovery and take a glimpse into the future by collecting together some of the latest research in directed aldol reactions. Even though the front cover looks like it might have arrived a month or so early, we think that all this top-quality research is more than just cause to celebrate at any time of the year! Photo credit: Jason Hollinger, http://flickr.com/photos/7147684@N03/543564833
Dr. Richard Threlfall
Article first published online: 12 NOV 2013 | DOI: 10.1002/ajoc.201300207
Article first published online: 12 NOV 2013 | DOI: 10.1002/ajoc.201390031
Article first published online: 12 NOV 2013 | DOI: 10.1002/ajoc.201381113
Dr. Wuming Yan, Prof. Dr. Xiaodong Shi and Dr. Cheng Zhong
Article first published online: 1 AUG 2013 | DOI: 10.1002/ajoc.201300048
Second to none: Secondary amines are well-known enamine and iminium catalysts that can also be used as Lewis bases for the activation of electron-deficient olefins. In this Focus Review, a series of systematic studies on activation of nitroolefins with secondary amines as Lewis bases that give different multicomponent condensation products are described. Asymmetric syntheses of heterocycles based on this strategy are also presented.
Dr. Seiji Shirakawa, Asuka Usui, Dr. S. B. Jennifer Kan and Prof. Dr. Keiji Maruoka
Article first published online: 12 SEP 2013 | DOI: 10.1002/ajoc.201300138
Cat on a hot tin radical: Chiral organotin-hydride-catalyzed enantioselective radical cyclization of aldehydes has been achieved. The reaction is efficiently promoted by a catalytic amount (10 mol %) of a chiral tin hydride to produce chromanol derivatives with moderate enantioselectivity. The utility of chiral organotin hydride was also demonstrated in catalytic enantioselective radical reduction.
Dr. Kenya Nakata, Tatsuya Tokumaru, Prof. Dr. Hidetoshi Iwamoto, Prof. Dr. Yutaka Nishigaichi and Prof. Dr. Isamu Shiina
Article first published online: 2 OCT 2013 | DOI: 10.1002/ajoc.201300139
Seventh heaven: The enantiodivergent synthesis of (+)- and (−)-centrolobines was achieved in a total of seven steps by using an asymmetric esterification in the presence of catalytic (R)-(+)-N-methylbenzoguanidine as the key reaction.
Correction: Correction: An Enantiodivergent Synthesis of (+)- and (−)-Centrolobines by Asymmetric Esterification Catalyzed by (R)-(+)-N-Methylbenzoguanidine ((R)-NMBG)
Vol. 3, Issue 1, 9, Article first published online: 17 JAN 2014
Kosuke Harada, Aya Nowaki and Prof. Dr. Jun-ichi Matsuo
Article first published online: 2 OCT 2013 | DOI: 10.1002/ajoc.201300156
Choice cuts: The formal [4+2] cycloaddition of 3-hydroxycyclobutanones to α,β-unsaturated ketones proceeds chemoselectively at the α,β-carbon–carbon double bond to afford cyclohexanone derivatives by using boron trifluoride etherate as a Lewis acid. In contrast, 3-ethoxycyclobutanone reacts at the carbonyl carbon–oxygen double bond to give dihydro-γ-pyrones.
Prof. Dr. Yutaka Watanabe, Mao Kawamoto, Hiroyuki Shintaku, Kae Tanabe, Dr. Hidetoshi Ohta and Dr. Minoru Hayashi
Article first published online: 6 NOV 2013 | DOI: 10.1002/ajoc.201300163
Diol A for activation: LiCl mediates mono-O-substitution of vicinal diol derivatives that are capable of forming intramolecular hydrogen bonds. The remarkable selectivity that leads to mono-O-substitution was demonstrated in polyols such as cyclitols and saccharides. SM=starting material.
Dr. Iwao Hachiya, Shingo Ito, Shota Kayaki and Prof. Dr. Makoto Shimizu
Article first published online: 22 OCT 2013 | DOI: 10.1002/ajoc.201300165
I, aldol: The iodoaldol reaction of γ-alkoxy-α,β-alkynyl ketones with aldehydes promoted by titanium tetraiodide proceeds to give the iodoaldol products in good yields with good to high diastereoselectivities. The iodinated addition products were transformed into tetrasubstituted furans by palladium-catalyzed Sonogashira coupling and subsequent cyclization. MOM=methoxymethyl ether.
Kazuya Tsuchida, Dr. Takuya Kochi and Prof. Dr. Fumitoshi Kakiuchi
Article first published online: 22 OCT 2013 | DOI: 10.1002/ajoc.201300168
Electric avenue: A copper-catalyzed electrochemical α-chlorination of 1,3-dicarbonyl compounds using hydrochloric acid as a chlorine source is described. Monochlorination products can be obtained from various 1,3-dicarbonyl compounds by using a reaction system where the only required reagents are a substrate, a solvent, a copper(II) salt and hydrochloric acid.
Takahiro N. Uehara, Prof. Dr. Junichiro Yamaguchi and Prof. Dr. Kenichiro Itami
Article first published online: 11 OCT 2013 | DOI: 10.1002/ajoc.201300172
A C4-selective CH arylation of 2-aminothiazoles with arylboronic acids takes place under the influence of Pd(OAc)2/phen/TEMPO/LiBF4 in air. During this study, a Pd-catalyzed CN cleavage/arylation of 2-aminobenzothiazoles with arylboronic acids has been discovered. bipy=2,2-bipyridyl; TEMPO=2,2,6,6-tetramethylpiperidin-1-oxyl.
Dr. Tsubasa Sakamoto, Kosaku Horiguchi, Dr. Kodai Saito, Dr. Keiji Mori and Prof. Dr. Takahiko Akiyama
Article first published online: 15 OCT 2013 | DOI: 10.1002/ajoc.201300174
Hold the benzothiazoline: Highly enantioselective transfer hydrogenation of difluoromethyl ketimines with benzothiazolines catalyzed by a chiral phosphoric acid furnishes α-difluoromethylated amines in good yields and with excellent enantioselectivity, irrespective of the stereochemistry of the starting materials. PMP=p-methoxyphenyl.
Daniel H. Lukamto, Peng Wang and Prof. Dr. Teck-Peng Loh
Article first published online: 5 NOV 2013 | DOI: 10.1002/ajoc.201300185
Looking forward: As fossil fuels deplete, 5-hydroxymethylfurfural (HMF) will play an important role in securing future energy and chemical feedstock needs as it is obtainable from renewable resources such as glucose and cellulose. We report a group of nonmetal Lewis-acid arylboronic acids that catalyse the formation of HMF in 3-ethyl-1-methyl-3 H-imidazol-1-ium chloride ([EMIM]Cl) from glucose and cellulose. EWG=electron-withdrawing group.
Dr. Manabu Hatano, Dr. Takahiro Horibe, Kenji Yamashita and Prof. Dr. Kazuaki Ishihara
Article first published online: 6 NOV 2013 | DOI: 10.1002/ajoc.201300190
Just another Mannich Mg: A recent development of chiral supramolecular magnesium(II) binaphtholates has inspired an investigation into two reactions, that is, the direct Mannich-type reaction and the hetero-Diels–Alder reaction, the mechanisms of which require further consideration. The results suggest that chiral di- and trinuclear supramolecular magnesium(II) complexes should play key roles as active catalytic species in these reactions. BINOL=1,1′-bi-2-naphthol.
Dr. Zhipeng Zhang and Prof. Dr. Benjamin List
Article first published online: 4 NOV 2013 | DOI: 10.1002/ajoc.201300182
Making progress: The kinetics of the disulfonimide-catalyzed Mukaiyama aldol reaction have been established by using the reaction progress kinetic analysis (RPKA) method. The reaction is first order with respect to catalyst and silyl ketene acetal, and has an order of 0.55 with respect to the aldehyde, which suggests the reversibility of the binding between the aldehyde and the actual catalyst.
Taku Kitanosono and Prof. Dr. Shū Kobayashi
Article first published online: 5 NOV 2013 | DOI: 10.1002/ajoc.201300201
Cop on to copper: An unprecedented copper(0) catalysis in water that entails chiral induction is proposed. A significant rate enhancement and stereocontrol are exerted discriminatorily in water. Several empirical facts suggest a new catalysis different from those of either copper(I) or copper(II) ions. The redox cycle mechanism proposed tentatively involves four steps (oxidative cyclometalation, transmetalation, hydrolysis, and reductive elimination).
Dr. Masaki Daini, Dr. Akihiko Yamamoto and Prof. Dr. Michinori Suginome
Article first published online: 10 OCT 2013 | DOI: 10.1002/ajoc.201300164
Triple take: Triggered by BCl bond activation, trans-addition of boron and carbon functional groups across a carbon–carbon triple bond takes place through transmetalation with alkynylstannanes and alkenylzirconium reagents, which leads to the synthesis of a variety of alkenylboronic acid derivatives.
Shuhei Kusumoto, Dr. Shingo Ito and Prof. Dr. Kyoko Nozaki
Article first published online: 17 SEP 2013 | DOI: 10.1002/ajoc.201300134
More haste, go direct: The direct aldol polymerization of acetaldehyde, a new approach for the synthesis of poly(vinyl alcohol) (PVA)- and poly(vinyl alcohol-co-ethylene) (EVA)-type oligomers, cooperatively catalyzed by organocatalysts and Brønsted acids was investigated. This conceptually new approach is an important step towards realizing the one-step synthesis of poly(vinyl alcohol)s from acetaldehyde with perfect atom economy.
Dr. Guangzhe Li, Dr. Mieko Arisawa and Dr. Masahiko Yamaguchi
Article first published online: 15 JUL 2013 | DOI: 10.1002/ajoc.201300094
Method of many talents: The synthesis and reactions of N-acylphthalimides are catalyzed by a complex of [RhH(PPh3)4] and 1,2-bis(diphenylphosphino)benzene (dppBz). N-Acylphthalimides can be synthesized by the imidation of thioesters or acid fluorides with N-(organothio)phthalimides. Thioesters, N-(phosphinoyl)phthalimides, acid fluorides, and N-(tetrafluoroaryl)phthalimides can also all be synthesized by using this method.
Dr. Hikaru Yanai, Nobuyuki Ishii, Prof. Dr. Takashi Matsumoto and Prof. Dr. Takeo Taguchi
Article first published online: 18 SEP 2013 | DOI: 10.1002/ajoc.201300157
Make your choice: By choosing the organic-acid catalysts, the reaction of lactones with ketene silyl acetals results in selective formation of simple Mukaiyama aldol adducts or olefination products. That is, in the presence of acidic zwitterions, the Mukaiyama aldol adducts were selectively obtained. In contrast, the reaction in the presence of a carbon acid catalyst gave the Z-olefination products. TBS=tert-butyldimethylsilyl.