Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• (Scheme 23). α,β-Unsaturated carbonyl compounds could also undergo a trans-bromination reaction efficiently within 40 min. Following to Wang’s report, Stolle and co-workers also reported a similar method of aryl bromination and chlorination using NaBr and NaCl, respectively, in the presence of oxidizing

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

• Kohei Yamada,
• Naoto Kamimura and
• Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

• materials, such as α-haloketones and primary amides [8], alkynes and nitriles [9], amines and α,β-unsaturated carbonyl compounds [10], etc. [11] have been reported. However, these reactions are often conducted under harsh reaction conditions and multistep syntheses of the starting materials are needed. ii

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

• Josef Jansa,
• Ramona Schmidt,
• Ashenafi Damtew Mamuye,
• Laura Castoldi,
• Alexander Roller,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2017, 13, 895–902, doi:10.3762/bjoc.13.90

• most common strategies employ reactions of 1,3-dicarbonyl compounds or α,β-unsaturated carbonyl compounds with substituted hydrazines [4][6][19]. To overcome the drawbacks of this method, namely insufficient regioselectivity [20], other accesses such as, for instance, regioselective metalations of N

Isoxazole derivatives as new nitric oxide elicitors in plants

• Anca Oancea,
• Emilian Georgescu,
• Florentina Georgescu,
• Alina Nicolescu,
• Elena Iulia Oprita,
• Catalina Tudora,
• Lucian Vladulescu,
• Marius-Constantin Vladulescu,
• Florin Oancea and
• Calin Deleanu

Beilstein J. Org. Chem. 2017, 13, 659–664, doi:10.3762/bjoc.13.65

• synthetic approaches towards the isoxazole core include the reactions of hydroxylamine with aryl-β-diketones [20], α,β-unsaturated carbonyl compounds [21], or α,β-unsaturated nitriles [22], and 1,3-dipolar cycloaddition reactions between alkenes or alkynes and nitrile oxides [23][24][25]. Nitrile oxides are

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• bond-donor activation of α,β-unsaturated carbonyl compounds in the [2 + 4] cycloaddition reaction of MVK and cyclopentadiene [88]. Halogen bond donor activation of imines in the [2 + 4] cycloaddition reaction of imine and Danishefsky’s diene [90]. Transfer hydrogenation catalyzed by a chiral halogen

Rh-Catalyzed reductive Mannich-type reaction and its application towards the synthesis of (±)-ezetimibe

• Motoyuki Isoda,
• Kazuyuki Sato,
• Yurika Kunugi,
• Satsuki Tokonishi,
• Atsushi Tarui,
• Masaaki Omote,
• Hideki Minami and
• Akira Ando

Beilstein J. Org. Chem. 2016, 12, 1608–1615, doi:10.3762/bjoc.12.157

• Mannich-type reactions have been reported to give β-amino esters and/or β-lactams by using metal enolates [10][11][12][13][14][15][16][17]. In contrast, most of reductive Mannich-type reactions using imines and α,β-unsaturated carbonyl compounds gave β-amino esters, but there are only a few reports for a

• results using similar conditions did not give the corresponding products such as β-propiolactones. It is well known that the substituents on the α- or β-position of α,β-unsaturated carbonyl compounds affect the yields and stereoselectivities [37]. A rhodium–hydride complex derived from [RhCl(cod)]2 seems

Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals

• Haipan Zhu,
• Peile Du,
• Jianjun Li,
• Ziyang Liao,
• Guohua Liu,
• Hao Li and
• Wei Wang

Beilstein J. Org. Chem. 2016, 12, 1340–1347, doi:10.3762/bjoc.12.127

• ]. However, it is difficult to apply the catalytic system for the regio-controlled reaction with C=C bonds in α,β-unsaturated carbonyl compounds, particularly enals. The highly active aldehyde functionality reacts more favorably with the D–A cyclopropane resulting 1,3-dipoles, as elegantly demonstrated by

Facile synthesis of 4H-chromene derivatives via base-mediated annulation of ortho-hydroxychalcones and 2-bromoallyl sulfones

• Srinivas Thadkapally,
• Athira C. Kunjachan and
• Rajeev S. Menon

Beilstein J. Org. Chem. 2016, 12, 16–21, doi:10.3762/bjoc.12.3

• ], multicomponent reactions [8], ring-closing metathesis approaches [9][10], tandem reactions of 1,3-dicarbonyl compounds [11][12] and cyclocondenzation reactions of salicylic aldehydes with α,β-unsaturated carbonyl compounds [13][14][15]. The utility of some of these methods are limited by drawbacks such as

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• coordination to the ruthenium atom, and finally, facilitates the initiating process. In the new catalyst 9, which is modified in the NHC ligand, different effects are responsible for its activity. According to Grubbs [31], catalyst 1 is able to react with α,β-unsaturated carbonyl compounds to form an enoic

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• of boron to α,β-unsaturated carbonyl compounds. Enantioenriched organoboron reagents are useful because they can be used in cross-coupling reactions [98][100] or they can be converted into the corresponding alcohol [101] while retaining the stereochemical information. Transition metals such as Cu

• [102][103][104][105][106][107][108][109][110][111][112], Rh [113][114][115], Ni [116][117], Pd [116][118] and Pt [119][120] have all been successfully used to catalyze the 1,4-additon of boron to α,β-unsaturated carbonyl compounds. Of the transition metals mentioned, copper is the most cost-effective

• )diboron to various α,β-unsaturated carbonyl compounds [121]. Use of bisboronic acid and tetrakis(dimethylamino)diboron provides boron sources that are more atom economical than B2pin2. Scheme 11 shows an example of the asymmetric 1,4-borylation where the authors used an α,β-unsaturated amide as the

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• ] annulation by combining MBH carbonates and electron-deficient alkenes into a single molecule (Scheme 37) [73]. In the presence of 10 mol % of D3, a variety of α,β-unsaturated carbonyl compounds were transformed efficiently in toluene at −5 °C to give optically active benzobicyclo[4.3.0] compounds 5 in

• development of chiral phosphine–assisted asymmetric Michael reactions has lagged behind other phosphine-catalyzed reactions. Recently, using bifunctional chiral amino acid–derived phosphines, Lu and co-workers developed asymmetric Michael additions of oxindoles to α,β-unsaturated carbonyl compounds (Scheme 55

Visible-light-induced, Ir-catalyzed reactions of N-methyl-N-((trimethylsilyl)methyl)aniline with cyclic α,β-unsaturated carbonyl compounds

• Dominik Lenhart and
• Thorsten Bach

Beilstein J. Org. Chem. 2014, 10, 890–896, doi:10.3762/bjoc.10.86

• -induced, iridium-catalyzed addition reactions to cyclic α,β-unsaturated carbonyl compounds. Typical reaction conditions included the use of one equivalent of the reaction substrate, 1.5 equivalents of the aniline and 2.5 mol % (in MeOH) or 1.0 mol % (in CH2Cl2) [Ir(ppy)2(dtbbpy)]BF4 as the catalyst. Two

• reactions to other cyclic α,β-unsaturated carbonyl compounds. In particular, we were interested to see whether cyclization reactions as for product 4 would be observed when using α,β-unsaturated lactones and lactams in combination with a silylated amine and an iridium catalyst. In this article, we provide

• readily not only to the previously reported cyclohexenone but to several cyclic α,β-unsaturated carbonyl compounds. Further reaction of the intermediate α-carbonyl radical was observed with five-membered substrates leading to synthetically interesting tricyclic products. The latter reaction suffers from

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• derivatives are treated with α,β-unsaturated carbonyl compounds in the presence of ammonia to initially form dihydropyridines 1.38, which can ultimately be converted into the corresponding aromatic pyridine upon oxidation with a variety of oxidants such as MnO2, HNO2, HNO3 or cerium ammonium nitrate (CAN

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• ] or α,β-unsaturated carbonyl compounds are attractive synthetic targets of high economic and scientific interest [11][12][13][14][15][16][17]. Allylic oxidations of olefins to enones have classically been performed with strong oxidants such as chromium or other metal-based reagents [18][19]. In

AgOTf-catalyzed one-pot reactions of 2-alkynylbenzaldoximes with α,β-unsaturated carbonyl compounds

• Qiuping Ding,
• Dan Wang,
• Puying Luo,
• Meiling Liu,
• Shouzhi Pu and
• Liyun Zhou

Beilstein J. Org. Chem. 2013, 9, 1949–1956, doi:10.3762/bjoc.9.231

• various α,β-unsaturated carbonyl compounds under mild conditions are described, which provides a facile and efficient pathway for the synthesis of 1-alkylated isoquinoline derivatives. The method tolerates a wide range of substrates and allows for the preparation of the products of interest in moderate to

• fragmentation from 2-alkynylbenzaldoximes and α,β-unsaturated carbonyl compounds. Based on previous results [36][37][38][39][41][42][43], we expect 2-alkynylbenzaldoxime 1 to easily convert at room temperature to isoquinoline N-oxide A by a AgOTf-catalyzed cyclization. Compound A produced in situ might undergo

• compounds 2a–g (Table 1). In most cases, substrate 1b reacted with α,β-unsaturated carbonyl compounds 2 leading to the corresponding 1-alkylated isoquinolines in moderate to excellent yields. For instance, the reaction with 2b under standard conditions gave rise to the desired product 3c in 81% yield (Table

Dipolar addition to cyclic vinyl sulfones leading to dual conformation tricycles

• Steven S. Y. Wong,
• Michael G. Brant,
• Christopher Barr,
• Allen G. Oliver and
• Jeremy E. Wulff

Beilstein J. Org. Chem. 2013, 9, 1419–1425, doi:10.3762/bjoc.9.159

• expedient regio- and stereospecific synthesis of five-membered ring N-, O- or S-containing heterocycles [4][5]. Various 1,3-dipoles can be used, including nitrones [6], azomethine ylides [7], diazoalkanes [8][9] and many others [10][11][12]. α,β-Unsaturated carbonyl compounds are often found to be good

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• (5), followed by an intramolecular aldol reaction and final dehydration to give the desired chromene derivative. Related work involving asymmetric reaction of salicylaldehyde derivatives and α,β-unsaturated carbonyl compounds in the synthesis of 2-phenylchromenes was reported by Li and co-workers

Synthesis and ring openings of cinnamate-derived N-unfunctionalised aziridines

• Alan Armstrong and
• Alexandra Ferguson

Beilstein J. Org. Chem. 2012, 8, 1747–1752, doi:10.3762/bjoc.8.199

• carbonyl compounds. Our method produces trans-NH-aziridines from α,β-unsaturated carbonyl compounds in good to excellent yield with high diastereoselectivity (Figure 1) [21]. An N–N ylide (aminimine) is the presumed active intermediate, formed from the reaction of a tertiary amine promoter and an aminating

• dihydroxylation, conversion to a cyclic sulfate, ring opening with azide, and finally ring closure to afford the NH-aziridine [18]. We recently reported [21][22] a nucleophilic aziridination methodology [23][24][25][26][27][28][29][30] that allows access to NH-aziridines in a single step from α,β-unsaturated

Michael-type addition of azoles of broad-scale acidity to methyl acrylate

• Sławomir Boncel,
• Kinga Saletra,
• Barbara Hefczyc and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2011, 7, 173–178, doi:10.3762/bjoc.7.24

• of various azoles to α,β-unsaturated carbonyl and nitro derivatives has been frequently exploited in the synthesis of precursors of biologically active compounds [3][7][8][9][10][11][12][13][14][15]. This reaction, although structurally restricted to α,β-unsaturated carbonyl compounds and their

Aroylketene dithioacetal chemistry: facile synthesis of 4-aroyl- 3-methylsulfanyl- 2-tosylpyrroles from aroylketene dithioacetals and TosMIC

• H. Surya Prakash Rao and
• S. Sivakumar

Beilstein J. Org. Chem. 2007, 3, No. 31, doi:10.1186/1860-5397-3-31

• to general α,β-unsaturated carbonyl compounds. Background The α-aroylketene dithioacetals (AKDTAs) 1 are useful three-carbon synthones extensively employed for the synthesis of a wide variety of heterocyclic compounds and also in several aromatic ring annulation reactions. [1][2] The AKDTAs are α,β

• -unsaturated carbonyl compounds with two electron-donating alkylsulafanyl groups on one end and an electron-withdrawing aroyl group at the other end of the double bond, i.e., they are "push-pull" alkenes. Depending on the nucleophile and the reaction conditions either 1,2- or 1,4-necleophilc additions on 1 are

One-pot synthesis of novel 1H-pyrimido[4,5-c][1,2]diazepines and pyrazolo[3,4-d]pyrimidines

• Dipak Prajapati,
• Partha P. Baruah,
• Baikuntha J. Gogoi and
• Jagir S. Sandhu

Beilstein J. Org. Chem. 2006, 2, No. 5, doi:10.1186/1860-5397-2-5

• through involvement of an azine (obtained from oxidation of hydrazine group). Similarly other α,β-unsaturated carbonyl compounds 2b-e were reacted and the corresponding pyrimido[1,2]diazepines 3b-e were obtained in 78–90% yields and were characterized fully by spectroscopic and elemental analyses. The IR