Metathesis access to monocyclic iminocyclitol-based therapeutic agents

• Ileana Dragutan,
• Valerian Dragutan,
• Carmen Mitan,
• Hermanus C.M. Vosloo,
• Lionel Delaude and
• Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

• ) and L-1-deoxyallonojirimycin (122) (Scheme 21) starting from protected diacetone glucose 115 [71]. Different pathways were devised for 91 and 122 via the epimeric RCM precursors 117 and 120, respectively. High yielding cyclization of these dienes, in the presence of the 1st-generation Grubbs catalyst

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• electrocyclic ring opening to yield eight-membered ring systems (Scheme 25) [73][80]. Another possibility to further transform the intermediates are Diels–Alder cycloadditions of the dienes formed by the ortho photocycloaddition [81]. Furthermore, Scharf demonstrated that he could trigger a photochemical

• of conjugated dienes or a second arene (usually higher aromatics), this photocycloaddition can also be carried out in a [4 + 4] mode to afford bicyclo[4.2.2]decatrienes and more complex homocycles [91][94][95]. In the non-sensitized irradiation of dianthryls, the [4 + 4] photocycloaddition [91

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

• Silke Dubberke,
• Muhammad Abbas and
• Bernhard Westermann

Beilstein J. Org. Chem. 2011, 7, 421–425, doi:10.3762/bjoc.7.54

• building block for the synthesis of dienes leading to nagilactones, 1b has been utilized for the preparation of ferroelectric liquid crystals [14][15]. Starting from (−)-1c a vast number of cyclohexene carboxylic acid-based natural products bearing additional alkyl substituents can be synthesized. These

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

• Ryuji Hayashi,
• John B. Feltenberger,
• Andrew G. Lohse,
• Mary C. Walton and
• Richard P. Hsung

Beilstein J. Org. Chem. 2011, 7, 410–420, doi:10.3762/bjoc.7.53

• Ryuji Hayashi John B. Feltenberger Andrew G. Lohse Mary C. Walton Richard P. Hsung Department of Chemistry and Division of Pharmaceutical Sciences, University of Wisconsin, Madison, WI 53705 10.3762/bjoc.7.53 Abstract Preparations of de novo acyclic 2-amido-dienes and 3-amido-trienes through 1,3

• -configuration. In addition, 6π-electron electrocyclic ring-closure could be carried out with 3-amido-trienes to afford cyclic 2-amido-dienes, and such electrocyclic ring-closure could be rendered in tandem with the 1,3-hydrogen shift. Keywords: allenamides; 2-amido-dienes; 3-amido-trienes; electrocyclic ring

• -closure; 1,3-hydrogen shift; isomerization; Introduction While allene isomerization to afford conjugated dienes is a well-known and thermodynamically favourable process, it is not trivial kinetically. A concerted allene isomerization leading to a diene involves a 1,3-hydrogen shift, which constitutes a

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany 10.3762/bjoc.7.39 Abstract Dienes embedded in quinolizidine and indolizidine structures can be prepared in four steps from cyclic nitrones and bicyclopropylidene. The key intermediates α-spirocyclopropanated N-heterocyclic ketones, generated via a

• domino 1,3-dipolar cycloaddition/thermal rearrangement sequence, were converted by Wittig methylenation to the corresponding vinylcyclopropanes (VCPs), which underwent rearrangement to 1,3-dienes in the presence of the Wilkinson Rh(I) complex under microwave heating. The previously unexplored Rh(I

• )-catalyzed opening of the VCP moiety embedded in an azapolycyclic system occurs at high temperature (110–130 °C) to afford the corresponding 1,3-dienes in moderate yield (34–53%). Keywords: nitrogen heterocycles; rearrangement; rhodium; small ring systems; spiro compounds; Introduction The cyclopropyl

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• Cedric Fischmeister Christian Bruneau UMR 6226-CNRS-Université de Rennes 1, Sciences Chimiques de Rennes, Catalyse et Organométalliques, Campus de Beaulieu, 263 avenue du général Leclerc, 35042 Rennes cedex, France 10.3762/bjoc.7.22 Abstract Conjugated 1,3-dienes are important building blocks in

• with ruthenium catalysts was initiated in 1997 when Mori [39] and Blechert [40] reported the first examples with ethylene and higher olefins, respectively. EYCM with ethylene The EYCM with ethylene is one of the simplest methods to generate conjugated dienes with two terminal methylene groups from

• synthesis of Anolignans [48] and another closely related example is shown in the preparation of Amphidinolide E [50][51] where the diene system is extended by further cross-metathesis with 2-methylpenta-1,4-diene (Figure 2). The Diels–Alder reaction is one of the most popular transformations of 1,3-dienes

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• , during the course of our investigations on the RCM of various α,ω-dienes catalyzed by complex 1, 31P NMR monitoring of the reaction media always showed a rapid disappearance of the signal originating from this precatalyst, and its replacement by a new singlet at ca. 40.5 ppm due to the ethylene complex 2

• demonstrated that homobimetallic ruthenium–indenylidene complex 1 is a suitable catalyst precursor for the tandem RCM/ATRC of polyhalogenated α,ω-dienes 4 and 8 into the corresponding bicyclic γ-lactam derivatives. A more complex cascade sequence involving RCM and ATRA reactions afforded γ-lactone 18 starting

New library of aminosulfonyl-tagged Hoveyda–Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations

• Etienne Borré,
• Frederic Caijo,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2010, 6, 1159–1166, doi:10.3762/bjoc.6.132

• catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemical functions. Keywords: cross-metathesis; kinetic studies; olefin metathesis; RCM; ruthenium

• weak influence on the behaviour of the catalysts in these cases. Finally, the reactivity profiles of 4a and 4g were compared in various metathesis reactions in order to evaluate the influence of the NHC ligand. The last point of our study was the comparison between catalysts in RCM of dienes or enynes

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• catalytic activities in RCM of linear dienes [32][34][35] and ROMP of cycloolefins [36][37][38][39][40] were reported. RCM studies with diethyl diallylmalonate and diallyl tosylamine as substrates showed an appreciable catalytic activity and selectivity for the 2nd generation 16-electron Ru–indenylidene

Synthesis of oxa-bridged derivatives from Diels–Alder bis-adducts of butadiene and 1,2,3,4-tetrahalo-5,5-dimethoxycyclopentadiene

• Faiz Ahmed Khan and
• Karuppasamy Parasuraman

Beilstein J. Org. Chem. 2010, 6, No. 64, doi:10.3762/bjoc.6.64

• reactions. We and other groups have demonstrated the utility of cyclic dienes for the synthesis of 2:1 Diels–Alder bis-adducts with 1,2,3,4-tetrahalo-5,5-dimethoxycyclopentadiene 1 [4][5][6][7]. In the case of cyclic dienes (or trienes) such as cyclohexa-1,4-diene and cycloheptatriene, endo-syn-endo

• -adducts of 1 with cyclic dienes. Diels–Alder reaction of 1a with 3-sulfolene. Synthesis of bis-oxa-bridged compounds 8 and 10 from bis-adducts 5 and 6. Diels–Alder reaction of 1b with 3-sulfolene. Synthesis of bis-oxa-bridged compounds 8 and 10 from bis-diketones 14 and 15. Supporting Information

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

• Satoru Arimitsu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

• some bioactive compounds [23][24][25]. Dienes 2a and 2b were used in Diels–Alder reactions with 4 and 6 to produce 5 and 4,4-difluoroisoquinolin-3-one derivatives 7, respectively, in excellent yield and good stereoselectivity (Scheme 1). Phenyl-substituted diene 2c gave no reaction, even after a longer

Novel loop-like aromatic compounds: a further step on the road to nanobelts and nanotubes

• Venkataramana Rajuri,
• Dariush Ajami,
• Gaston R. Schaller,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2010, 6, No. 30, doi:10.3762/bjoc.6.30

• the most electron deficient dienes used in Diels–Alder reactions and is readily accessible by the reaction of tetrachlorothiophene with peroxytrifluoroacetic acid [24][25]. The Diels–Alder reaction of 1 with an excess of diene 10, followed by instantaneous elimination of sulfur dioxide furnished

• and 7 using pyridazine, 1,2-bis(dibromomethyl)benzene and 2,3,4,5-tetrachlorothiophene-1,1-dioxide as dienes the loop-like molecules 2, 3, 5b, and 6 were obtained. All structures were verified by X-ray crystal structure analysis. ORTEP drawing of the crystal structures: a) 2 and b) 3. For additional

Fused bicyclic piperidines and dihydropyridines by dearomatising cyclisation of the enolates of nicotinyl-substituted esters and ketones

• Heloise Brice,
• Jonathan Clayden and
• Stuart D. Hamilton

Beilstein J. Org. Chem. 2010, 6, No. 22, doi:10.3762/bjoc.6.22

• mixture of dienes 11 gave ester 12 after hydrogenation (Scheme 4). It proved challenging to isolate cleanly the silyl ketene acetal derived from 12, so instead we decided to form and cyclise the silyl derivative in a single pot. Thus, ester 12 was added to LDA at −78 °C, and the enolate quenched with

Solvent-free phase-vanishing reactions with PTFE (Teflon^®) as a phase screen

• Kevin Pels and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2009, 5, No. 75, doi:10.3762/bjoc.5.75

• and either acrylic acid or dimethyl fumarate react at a relatively high rate [26]. As most Diels-Alder reactions are relatively slow, and most dienes are highly reactive towards halogens, it may be necessary to carry out sequential reactions. Solvent-free PV-PTFE reaction design is simple and

Preparation and Diels–Alder/cross coupling reactions of a 2-diethanolaminoboron- substituted 1,3-diene

• Liqiong Wang,
• Cynthia S. Day,
• Marcus W. Wright and
• Mark E. Welker

Beilstein J. Org. Chem. 2009, 5, No. 45, doi:10.3762/bjoc.5.45

• substituted dienes are stable but their organic solvent solubility is not ideal. Preparation of more highly substituted BF3 dienes also requires a transmetallation protocol which yields a Grignard-BF3 by-product which has to be separated from the desired diene [9]. To overcome these methodology challenges we

• have begun to prepare diethanolaminoboron substituted dienes and we communicate our first results in this area here. Results and Discussion The diethanolamine boronyl substituted diene 2 was obtained as white needles on a several gram scale from a simple procedure which involved preparing the Grignard

• than the BF3 substituted diene. In the solid state (Figure 1, see Supporting Information), C(1)–C(2) and C(2)–C(3) bond lengths were virtually identical in both dienes whereas B–C(2) (1.609(5) Å vs 1.576(13) Å) and C(3)–C(4) (1.308(6) Å vs 1.279(13) Å) were significantly longer in the diethanolamine

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• diastereomers, it was suggested that the absolute configuration of natural cis-solamin was 71a. In 2002, Brown’s group [43] also reported the synthesis of cis-solamin (71a) and its diastereomer 71b using the diastereoselective permanganate-promoted oxidative cyclization of 1,5-dienes to create the THF diol core

Diels- Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton

• Natsuno Etomi,
• Takuya Kumamoto,
• Waka Nakanishi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2008, 4, No. 15, doi:10.3762/bjoc.4.15

• salt for the synthesis of bromonaphthalene 6 [24] hampered large-scale synthesis of 4. Towards a solution to this problem, we planned the synthesis of 4 via A-ring construction by DAR of indanone-type compounds and oxygenated dienes: i. e. 1) DAR of indanetrione 8 and 1-methoxy-1,3-butadiene (7) (path

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

• Ishmael B. Masesane,
• Andrei S. Batsanov,
• Judith A. K. Howard,
• Raju Mondal and
• Patrick G. Steel

Beilstein J. Org. Chem. 2006, 2, No. 9, doi:10.1186/1860-5397-2-9

• . 3,4,5-Trihydroxy-2-aminocyclohexanecarboxylic acids The final group of targets we wished to generate was the trihydroxy analogs. Initial attempts addressed the generation of the syn 4,5 set. Consequently, OsO4 mediated dihydroxylation and subsequent peracylation of dienes 4 and 5 proved to be facio

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• concerning biological activity of C8-glycomimetics are seldom, the reported activities are often weak [24][25][26][27][28][29][30]. In summary, utilizing the readily available polyhydroxylated L-ido or D-manno-cyclooctenes, coming from ring closing metathesis of C2-symmetrical 1,9-dienes, we have