Asymmetric total synthesis of smyrindiol employing an organocatalytic aldol key step

• Dieter Enders,
• Jeanne Fronert,
• Tom Bisschops and
• Florian Boeck

Beilstein J. Org. Chem. 2012, 8, 1112–1117, doi:10.3762/bjoc.8.123

• found that other protecting groups were either not compatible with the reaction conditions towards acetonide 15 or were found to be impossible to cleave afterwards while leaving the rest of the molecule intact. Since we were unable to conduct a selective mono-allylation of the hydroxy group in the 4

Synthesis of axially chiral oxazoline–carbene ligands with an N-naphthyl framework and a study of their coordination with AuCl·SMe₂

• Feijun Wang,
• Shengke Li,
• Mingliang Qu,
• Mei-Xin Zhao,
• Lian-Jun Liu and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 726–731, doi:10.3762/bjoc.8.81

• % ee of the (E)-allylation products and 92% ee of the recovered Morita–Baylis–Hillman adducts. These intriguing results stimulated us to further develop the axially chiral oxazoline–carbene ligands 7 with an N-naphthyl framework and to evaluate their coordination with AuCl·SMe2. Results and Discussion

Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

• Elizabeth P. Jones,
• Peter Jones,
• Andrew J. P. White and
• Anthony G. M. Barrett

Beilstein J. Org. Chem. 2011, 7, 1570–1576, doi:10.3762/bjoc.7.185

• publication, we demonstrated the scope of the methodology over a range of ortho-lithiation benzyne precursors. To establish that any one of these precursors could be used to form quaternary adducts, we subjected the benzylation conditions to precursor 2b and the allylation conditions to precursor 2c

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents

• Paul Knochel,
• Matthias A. Schade,
• Sebastian Bernhardt,
• Georg Manolikakes,
• Albrecht Metzger,
• Fabian M. Piller,
• Christoph J. Rohbogner and
• Marc Mosrin

Beilstein J. Org. Chem. 2011, 7, 1261–1277, doi:10.3762/bjoc.7.147

• reagents 5 and 8 are obtained at 25 °C in quantitative yield. The allylation of pyridylzinc derivative 8 with allyl bromide provides pyridine 9 in 85% yield [6]. Interestingly, a diiodide, such as 2,5-diiodothiophene (10) reacts selectively with Zn and LiCl to provide the iodothienyl ketone 11 in 94% yield

• after benzoylation. Subsequent treatment of 11 with a second amount of Zn and LiCl (1.4 equiv) provides a new intermediate zinc reagent within 10 min, which after allylation provides the 2,5-disubstituted thiophene 12 in 87% yield (Scheme 3) [6]. The insertion reaction proceeds best with aryl and

• -coupling (Negishi reaction) affords the 5-arylated furan 15 in 89% yield. Interestingly, a high chemoselectivity is observed with several heterocyclic dihalides [8][9]. Thus, the tribromopyrimidine 16 provides only the 4-zincated pyrimidine 17. After allylation, the expected allylated pyrimidine 18 is

Gold(I)-catalyzed synthesis of γ-vinylbutyrolactones by intramolecular oxaallylic alkylation with alcohols

• Michel Chiarucci,
• Mirko Locritani,
• Gianpiero Cera and
• Marco Bandini

Beilstein J. Org. Chem. 2011, 7, 1198–1204, doi:10.3762/bjoc.7.139

• the gold-catalyzed intramolecular allylation of 1.a Supporting Information Supporting Information File 172: Experimental details and characterization of the synthesized compounds. Acknowledgment Acknowledgment is made to Progetto FIRB “Futuro in Ricerca” Innovative sustainable synthetic

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

• catalytic amount of phosphite–gold(I) pre-catalyst and a silver additive. Notably, the addition is regioselective for the allene terminus, and generates (E)-allylation products 202. The direct C–H functionalization of indoles or pyrroles is an efficient method for the introduction of vinyl and aryl groups

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• intermediates can be transmetalated in situ with dimethylzinc or zinc chloride, which facilities the cross-coupling process to give N-unprotected homoallylic amines after aqueous workup. All products were isolated as single regio- and diastereoisomers, and the regioselectivity of the allylation step was shown

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

• 69 provides an attractive starting point since it reacts with organometallic reagents with a high degree of diastereoselectivity and minimal racemization. N-allylation (allyl iodide/NaH; 95% yield) of an intermediate derived from 70 gave the diolefin product 71, which was then subjected to RCM

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• formation reactions in synthetic organic chemistry have attracted considerable attention in recent years [1]. Palladium-catalyzed allylation is also a particularly useful method for the activation of allylic substrates [2]. Trost et al. described a highly stereoselective synthesis of oxazolidinone 2

Cross-metathesis of allylcarboranes with O-allylcyclodextrins

• Ivan Šnajdr,
• Zbyněk Janoušek,
• Jindřich Jindřich and
• Martin Kotora

Beilstein J. Org. Chem. 2010, 6, 1099–1105, doi:10.3762/bjoc.6.126

• carried out according to the previously reported procedures [8]. O-Allylcyclodextrins 2 were prepared by allylation of β-cyclodextrins under various reaction conditions (2I-O-allyl-β-cyclodextrin for 2a [22], 3I-O-allyl-β-cyclodextrin for 2b [23], and 6I-O-allyl-β-cyclodextrin for 2c) followed by

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• attractive precursors for organic synthesis as there are several possibilities for further transforming the exocyclic double bonds. Typically, in transition-metal-catalyzed allylation reactions reactive, metal-coordinated allyl cations are formed which may lead to linear and branched products, whereby the

• product ratio is dependent on the catalyst employed (Scheme 23). To date, only few FC-type allylations with environmentally benign allylating reagents, such as allyl alcohols have been reported. Here Shimizu and co-workers did seminal work by developing a Mo(CO)6- and W(CO)6-catalyzed allylation and

• 54b did not give the corresponding alkylated cresol 59. Instead the chromane 60 was observed in 28% yield (Scheme 25). This reaction has recently been improved and extended by applying MoCl(CO)3Cp and [Mo(CO)3Cp]2 as transition-metal catalysts [76]. A very similar FC allylation/hydroaralyation

Influence of spacer chain lengths and polar terminal groups on the mesomorphic properties of tethered 5-phenylpyrimidines

• Gundula F. Starkulla,
• Elisabeth Kapatsina,
• Angelika Baro,
• Frank Giesselmann,
• Stefan Tussetschläger,
• Martin Kaller and
• Sabine Laschat

Beilstein J. Org. Chem. 2009, 5, No. 63, doi:10.3762/bjoc.5.63

• 23 up to 60% yield. When 1,3-dibromopropane was used, 27% of the elimination product 9 was isolated as byproduct. For comparison the corresponding 4-allyloxy-4′-octylbiphenyl 11 was prepared in 49% yield by allylation of 4-hydroxy-4′-octylbiphenyl. Compound 3a was obtained by etherification of 5-(4

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

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

• sodium borohydride reduction of the remaining aldehyde, followed by alkylation of the resulting primary alcohol with methyl isocyanate to give 184. 6.4. Coleman. Allylation reaction and 1,4-quinone addition The Coleman group proposed an elegant synthesis of an enantiomerically pure mitosane. One of the

• key transformations involved an allylation reaction [139][140][141][142][143] between the allyl stannane 185 and the iminium formed in situ from the enantiomerically pure pyrrolidine 187 (Scheme 51) [144]. The reaction showed good diastereoselectivity, giving a 3:1 ratio of diastereomers favoring the

• substituent. When the allylation reaction was done with the iminium derived from pyrrolidine 186, no diastereoselectivity for the formation of 188 was observed. The bulkiness of the benzyl carbamate now proximal to the iminium ion was responsible for this poor result. The pyrrolidine 187 was synthesized from

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• donor in specific organometallic reactions, such as the chromium-mediated allylation of aldehydes and ketones [54][55] and the palladium-catalyzed reductive homo-coupling of aryl halides to afford the corresponding biaryls [56][57][58][59] illustrate further versatility of the reagent. The fact that

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

• , Pagenkopf’s group reported the total synthesis of bullatacin (311) in an efficient route from commercial starting materials (Scheme 44) [105]. The bis(THF) core 319 was constructed from bis-epoxide 318 through double allylation and oxidative cyclization. Then titanium acetylide 320 was reacted with bis(THF

End game strategies towards the total synthesis of vibsanin E, 3-hydroxyvibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A

• Brett D. Schwartz,
• Craig M. Williams and
• Paul V. Bernhardt

Beilstein J. Org. Chem. 2008, 4, No. 34, doi:10.3762/bjoc.4.34

• directed towards bis-epi-3-hydroxyvibsanin E 51. This manoeuvre was further justified by the fact that diketone 40 was readily available via the allylation/Wacker protocol as described in Scheme 6. Considering the knowledge gained in Scheme 8, it was perceived best not to perform tricarbonyl reduction then

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• persulfate-pyridine system [32]. The ensuing Ag(I) catalyzed oxidative radical cyclization proceeded in 85% yield. Racemic ketone 43 underwent regio- and stereoselective allylation under Corey-Enders conditions to provide olefin 44, which was subjected to Lemieux-Johnson cleavage to corresponding aldehyde

The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines

• Matthew J. McGrath and
• Carsten Bolm

Beilstein J. Org. Chem. 2007, 3, No. 33, doi:10.1186/1860-5397-3-33

• in low yield (Table 2, Entry 4) presumably due to facile deprotonation of the product under the reaction conditions. A moderate yield was also obtained on allylation with allyl iodide (Table 2, Entry 5) but in this case the enantiomers could not be resolved by HPLC using a chiral column. A benzylic

Tether- directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

• Peter J. Jervis and
• Liam R. Cox

Beilstein J. Org. Chem. 2007, 3, No. 6, doi:10.1186/1860-5397-3-6

• -mediated allylation to proceed in an intramolecular sense and therefore receive all the benefits associated with such processes. However, with the ability to cleave the tether post allylation, a product that is the result of a net intermolecular reaction can be obtained. In the present study, four

• diastereoisomeric β-silyloxy-α-methyl aldehydes, which contain an allylsilane tethered through the β-carbinol centre, have been prepared, in order to probe how the relative configuration of the two stereogenic centres affects the efficiency and selectivity of the intramolecular allylation. Results Syn-aldehydes

• , syn-4a and syn-4b, both react poorly, affording all four possible diastereoisomeric oxasilacycle products. In contrast, the anti aldehydes anti-4a and anti-4b react analogously to substrates that lack substitution at the α-site, affording only two of the four possible allylation products. Conclusion

Reaction of benzoxasilocines with aromatic aldehydes: Synthesis of homopterocarpans

• Míriam Álvarez-Corral,
• Cristóbal López-Sánchez,
• Leticia Jiménez-González,
• Antonio Rosales,
• Manuel Muñoz-Dorado and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2007, 3, No. 5, doi:10.1186/1860-5397-3-5

• of allylation reactions, [1] which has been used for the formation of carbo- and heterocycles. [2][3] We have applied it to the stereoselective synthesis of dihydrobenzofurans by means of the condensation of benzoxasilepines with aromatic aldehydes in the presence of Lewis acids. [4][5] Using this

Contemporary organosilicon chemistry

• Steve Marsden

Beilstein J. Org. Chem. 2007, 3, No. 4, doi:10.1186/1860-5397-3-4

• for asymmetric synthesis, and a new method for the electrochemical generation of silyl cations. Additionally, the unique nature of internet-based publishing means that the Series can grow as additional contributions are received: future papers in areas including allylation chemistry, stereoselective

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

• rearrangement (S)-2(methoxymethyl)pyrrolidine 22 was then explored as the chiral auxiliary.[25] This auxiliary was selected to include a co-ordinating oxygen in place of the bulky diphenylmethane group in 14 to compare steric versus co-ordination effects. Allylation then gave 23 as the required aza-Claisen

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• ). The N,O acetal was substituted,[40] both by reduction (→ 13) and by allylation (→ 14); the allylation reaction was highly diastereoselective (>95:<5 syn:anti), presumably as a result of a strong stereoelectronic preference for pseudo-axial attack on the intermediate iminium ion (with a pseudoaxial[40