Meta-metallation of N,N-dimethylaniline: Contrasting direct sodium-mediated zincation with indirect sodiation-dialkylzinc co-complexation

• David R. Armstrong,
• Liam Balloch,
• Eva Hevia,
• Alan R. Kennedy,
• Robert E. Mulvey,
• Charles T. O'Hara and
• Stuart D. Robertson

Beilstein J. Org. Chem. 2011, 7, 1234–1248, doi:10.3762/bjoc.7.144

• emphasise the synthetic utility of the AMMZn reaction with the employment of a synergic bimetallic base providing entry to previously inaccessible metallation regioselectivities. The AMMZn of N,N-dimethylaniline by sodium zincate 1 ((TMEDA)Na(TMP)(t-Bu)Zn(t-Bu)) has been shown to afford a mixture of ortho

Directed aromatic functionalization

• Victor Snieckus

Beilstein J. Org. Chem. 2011, 7, 1215–1218, doi:10.3762/bjoc.7.141

• ], in spite of their considerable synthetic utility, are given sparse mention. By the time students reach the upper years of study, aromatic chemistry receives the label “classical” and is disregarded or relegated to brief coverage. Apart from in English schools [13], heteroaromatic chemistry suffers

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• previously suggested intermediate II (Scheme 1). The synthetic utility of these cycloadditions has also been explored, and recently an intramolecular version was applied to the synthesis of the angucyclinone antibiotics, (+)-ochromycinone and (+)-rubiginone B2 [29][30][31][32]. Closely related dipolar

• increased the scope and synthetic utility of the process [98]. In general, the reactions are completely diastereoselective affording the products as a result of an exo-like approach of the allyl cation to the diene. The reaction tolerates a variety of substituents on the allene and the diene, providing a

Homocoupling of aryl halides in flow: Space integration of lithiation and FeCl₃ promoted homocoupling

• Aiichiro Nagaki,
• Yuki Uesugi,
• Yutaka Tomida and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2011, 7, 1064–1069, doi:10.3762/bjoc.7.122

• functional groups, can be used for this transformation in the integrated flow microreactor system. Hence, the method greatly enhances the synthetic utility of aryllithium compounds and adds a new dimension to the chemistry of coupling reactions. Flow microreactor system for halogen–lithium exchange of aryl

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

• gold pre-catalyst 125 featuring a P,N-ligand that has significantly extended the substrate scope and synthetic utility of alkyne hydroamination [60]. The hydroamination of unsymmetrical internal aryl acetylenes 126 with dialkylamines 127 has been achieved with synthetically useful regioselectivities

Synthetic applications of gold-catalyzed ring expansions

• David Garayalde and
• Cristina Nevado

Beilstein J. Org. Chem. 2011, 7, 767–780, doi:10.3762/bjoc.7.87

• , such that a consecutive cyclopropyl ring expansion affords the bicyclic [3.2.0]heptane skeleton 68 in excellent yield and selectivity [53]. Treatment of 68 with a protic acid in water should activate the enone system triggering the nucleophilic attack of water to give hydroxy ketones 69. The synthetic

• utility of the method can be easily recognized by an examination of the structure of natural products such as repraesentin F, whose core largely comprises the structural motifs generated in this gold-catalyzed cascade. 5 Ring expansions involving enynes The gold-catalyzed heteroatom-assisted 1,2-shift

Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters

• Haruo Aikawa,
• Tetsuro Kaneko,
• Naoki Asao and
• Yoshinori Yamamoto

Beilstein J. Org. Chem. 2011, 7, 648–652, doi:10.3762/bjoc.7.76

• -position, such as 1f. Further studies to elucidate the mechanism of this reaction and to extend the scope of synthetic utility are underway. Alkylation of silyl enol ethers. Plausible mechanism for the alkylation of silyl enol ether. Gold-catalyzed isomerism of silyl enol ether. Gold-catalyzed alkylation

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• thiocarbamates Carbon–carbon bond formation in configurationally stable α-thioorganolithiums allows access to non-racemic tertiary thiols of varying structure and complexity. Hoppe’s extensive studies of lithiated thiocarbamates have continued to display the synthetic utility of these species in the formation of

A thermally-induced, tandem [3,3]-sigmatropic rearrangement/[2 + 2] cycloaddition approach to carbocyclic spirooxindoles

• Kay M. Brummond and
• Joshua M. Osbourn

Beilstein J. Org. Chem. 2010, 6, No. 33, doi:10.3762/bjoc.6.33

• complexity. Furthermore, this approach includes a rare example of a thermal [3,3]-sigmatropic rearrangement of a propargylic acetate while metal catalyzed rearrangements of the propargyl acetates are common. Work is currently underway to expand the synthetic utility of this reaction. Experimental

Radical cascades using enantioenriched 7-azabenzonorbornenes and their applications in synthesis

• David M. Hodgson and
• Leonard H. Winning

Beilstein J. Org. Chem. 2008, 4, No. 38, doi:10.3762/bjoc.4.38

• species can lead to an overall 1,2-aryl (neophyl) migration [20]. We have previously communicated our initial findings in the application of tandem radical cascades toward the 2-aza-5,6-benzonorbornenyl system [21]. We now present our wider investigations of this system and its synthetic utility. Results

Synthesis of the Benzo- fused Indolizidine Alkaloid Mimics

• Daniel L. Comins and
• Kazuhiro Higuchi

Beilstein J. Org. Chem. 2007, 3, No. 42, doi:10.1186/1860-5397-3-42

• chemical library preparation. Background As part of a program directed at studying the synthesis and synthetic utility of N-acyldihydropyridones, the heterocycles 1 were developed as useful building blocks for alkaloid synthesis (Figure 1). [1][2] Biologically active indolizidine alkaloids [3] such as

The enantiospecific synthesis of (+)-monomorine I using a 5-endo- trig cyclisation strategy

• Malcolm B. Berry,
• Donald Craig,
• Philip S. Jones and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2007, 3, No. 39, doi:10.1186/1860-5397-3-39

• , (+)-monomorine I. [10][11][12][13] We have briefly described this work in a previous communication. [4] Results and Discussion The pyrrolidine ring is an important structural motif that occurs in a range of pheromones, venoms and drug candidates. [14] In order to demonstrate the synthetic utility of the sulfone

Allylsilanes in the synthesis of three to seven membered rings: the silylcuprate strategy

• Asunción Barbero,
• Francisco J. Pulido and
• M. Carmen Sañudo

Beilstein J. Org. Chem. 2007, 3, No. 16, doi:10.1186/1860-5397-3-16

• substituted cyclobutenes after cyclization of the vinylsilane or vinylstannane intermediate. [23] Cyclization of the corresponding vinylsilanes gave poor results of no synthetic utility, however the vinylstannane strategy results in formation of 1- and 3-substituted cyclobutenes 42 and 43 in good yield

Synthesis of spiropyrans: H-abstractions in 3-cycloalkenyloxybenzopyrans

• Satish C. Gupta,
• Mandeep Thakur,
• Somesh Sharma,
• Urmila Berar,
• Surinder Berar and
• Ramesh C. Kamboj

Beilstein J. Org. Chem. 2007, 3, No. 14, doi:10.1186/1860-5397-3-14

• cyclisations and [4+2] cycloadditions. [11][12][13][14][15][16] These methods being specific in nature for a particular spirocyclic compound, offer limited synthetic utility. In the past, we have investigated the use of photochemical methods for the synthesis of organic molecules like vinyl ethers, [17

Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes

• Stephen P. Marsden and
• Pascal C. Ducept

Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5

• chemistry undertaken by allenylsilanes, we expect that these new highly functionalised members of the class will find broad synthetic utility. Our own studies on their application in heterocyclic synthesis will be disclosed in due course. Description of Supporting Information Supporting Information features