Combined directed ortho-zincation and palladium-catalyzed strategies: Synthesis of 4,n-dimethoxy-substituted benzo[b]furans

• Verónica Guilarte,
• M. Pilar Castroviejo,
• Estela Álvarez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 1255–1260, doi:10.3762/bjoc.7.146

• ring system, the cyclodehydration of α-aryloxy ketones [29], the Claisen rearrangement of an allyl aryl ether followed by Pd-catalyzed intramolecular oxidative cyclization [30], and the tandem Sonogashira coupling/heterocyclization of 2-halophenols with terminal alkynes [31], are some of the most used

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• % PPh3AuCl/5 mol % AgOTf in dichloroethane at 80 °C gave alkylidenecyclobutanamine 160 in 65% yield as a single olefin isomer (Scheme 28). The formation of tri- and tetrasubstituted pyrroles 163 [74] via cationic N-heterocyclic carbene–gold(I) complex catalyzed amino Claisen rearrangement of N-propargyl-β

Gold(I)-catalyzed formation of furans by a Claisen-type rearrangement of ynenyl allyl ethers

• Florin M. Istrate and
• Fabien Gagosz

Beilstein J. Org. Chem. 2011, 7, 878–885, doi:10.3762/bjoc.7.100

• involves a Claisen-type rearrangement that allows the efficient creation of quaternary centers under mild experimental conditions. Keywords: Claisen rearrangement; furans; gold-catalysis; quaternary centers; Findings Furans represent an important class of heteroaromatic compounds, which are found in a

Highly efficient gold(I)-catalyzed Overman rearrangement in water

• Dong Xing and
• Dan Yang

Beilstein J. Org. Chem. 2011, 7, 781–785, doi:10.3762/bjoc.7.88

• environmentally benign and scalable protocol, a series of C3-alkyl substituted allylic trichloroacetamides were synthesized in good to high yields. Keywords: allylic trichloroacetamides; allylic trichloroacetimidate; gold(I) chloride; Overman rearrangement; water; Introduction The aza-Claisen rearrangement of

• moderate yields were achieved [25][26][27][28]. Very recently, our group developed an efficient gold(I)-catalyzed decarboxylative aza-Claisen rearrangement of allylic N-tosylcarbamates for the synthesis of N-tosyl allylic amines [29]. This reaction was performed in water and therefore represented an

Total synthesis of (±)-coerulescine and (±)-horsfiline

• Mukund G. Kulkarni,
• Attrimuni P. Dhondge,
• Sanjay W. Chavhan,
• Ajit S. Borhade,
• Yunnus B. Shaikh,
• Deekshaputra R. Birhade,
• Mayur P. Desai and
• Nagorao R. Dhatrak

Beilstein J. Org. Chem. 2010, 6, 876–879, doi:10.3762/bjoc.6.103

• rearrangement protocol was applied to obtain 3-allyl oxindole. This oxindole was then converted to (±)-coerulescine and (±)-horsfiline. Keywords: alkaloids; Claisen rearrangement; Jones oxidation; spiro-oxindole; Wittig olefination; Introduction The spiro[pyrrolidin-3,3′-oxindole] ring system is a widely

• [31], dimethyldioxirane (DMDO) mediated oxidation [32], and by tandem intramolecular photocycloaddition–retro-Mannich reaction [33]. The Wittig olefination–Claisen rearrangement protocol [35] provides a ready access to 4-pentenals, which have served as versatile intermediates for the synthesis of a

• allyl vinyl ethers was heated in refluxing xylene to effect the Claisen rearrangement to obtain 4-pentenal 6 in 85% yield. Aldehyde 6 was transformed into acid 7 by Jones oxidation, which was immediately converted to the ethyl ester 8. Subsequently, reduction of the compound 8 with Zn and NH4Cl resulted

An enantiomerically pure siderophore type ligand for the diastereoselective 1 : 1 complexation of lanthanide(III) ions

• Markus Albrecht,
• Olga Osetska,
• Thomas Abel,
• Gebhard Haberhauer and
• Eva Ziegler

Beilstein J. Org. Chem. 2009, 5, No. 78, doi:10.3762/bjoc.5.78

• enantiomerically pure “non-natural” peptide moiety [25], which organizes three tridenate metal binding sites in one direction [26][27][28]. The synthesis of the compound is facile and utilizes a multiple Claisen-rearrangement reaction as introduced by Hiratani as the keystep [29][30]. UV and CD titration

• to be tridentate by addition of diethylamide to the 2-position. Recently 2-amido-8-hydoxyquinolines were shown to be good ligands for the 3 : 1 complexation of lanthanide(III)ions [34][35]. The aryl ether of 3 bears already the allylic unit for Claisen rearrangement as well as the chloride leaving

• group for the attachment of other units. Coupling of 2 with three equivalents of 3 results in the formation of the ligand precursor 4. The triple Claisen rearrangement of 4 proceeds at 165 °C under inert atmosphere (N2) within 6 hours [36]. No epimerization occurs at the chiral carbon atoms of the

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• other mammal and vegetal alkaloids. The Naruta–Maruyama group exploited this reaction for the synthesis of a leucoaziridinomitosane based on the retrosynthesis shown in Scheme 12 [57][58]. The synthesis began with a Claisen rearrangement of the pentadienyl aryl ether 47 under Lewis acidic conditions

• leaving group X free for nucleophilic displacement with the nitrogen of the newly formed pyrroline. The synthesis began by Mitsunobu coupling of phenol 76 with allylic alcohol 77 to give ether 78, which was heated in N,N-dimethylaniline to trigger a Claisen rearrangement (Scheme 22). A sequence of

• requisite eight membered ring was formed by the well-established chemistry of quinones using an intramolecular Michael addition by the primary amine 157 (Scheme 44) [118]. The synthesis began with the known phenol 158 which was reacted with allyl bromide to trigger a Claisen rearrangement (Scheme 45). This

Understanding the mechanism of Pd-catalyzed allylic substitution of the cyclic difluorinated carbonates

• Jun Xu,
• Xiao-Long Qiu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2008, 4, No. 18, doi:10.3762/bjoc.4.18

• prepare potential bioactive fluorinated nucleosides, our group recently described the stereoselective synthesis of 3',3'-difluoro-4',5'-unsaturated OTCs 2–3 and 5 [11]. The whole synthesis highlighted the stereoselective Reformatskii-Claisen rearrangement, ring-closing metathesis (RCM), and Pd-catalyzed

Stereoselective α-fluoroamide and α-fluoro- γ-lactone synthesis by an asymmetric zwitterionic aza-Claisen rearrangement

• Kenny Tenza,
• Julian S. Northen,
• David O'Hagan and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2005, 1, No. 13, doi:10.1186/1860-5397-1-13

• straightforward asymmetric method to this class of compounds, utilising the zwitterionic aza-Claisen rearrangement by reacting α-fluoroacid chlorides and homochiral N-allylpyrrolidines as starting materials. Results Treatment of N-allylmorpholine with 2-fluoropropionyl chloride under Yb(OTf)3 catalysis generated

• the zwitterionic aza-Claisen rearrangement product in good yield and demonstrated the chemical feasibility of the approach. For the asymmetric reaction, N-allyl-(S)-2-(methoxymethyl)pyrrolidine was treated with either 2-fluoropropionyl chloride or 2-fluorophenylacetic acid chloride under similar

• are finding increasing utility in pharmaceutical, fine chemicals and materials research. The zwitterionic aza-Claisen rearrangement proved to be an effective and competitive complement to asymmetric electrophilic fluorination strategies and provides access to versatile synthetic intermediates with