Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• significant catalytic activity was observed in this specific model reaction (Scheme 3). The fluorination of cyanoester 3 with F–TEDA was not accelerated by any of the potential catalysts investigated (TiCl4, BF3·Et2O, SnCl4, Sn(OTf)2, AlCl3, Mg(OTf)2, ZnF2 or SbF3). The conversion 3→3-F in a blank reaction

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• protected by the silylation with hexamethyldisilazane. Subsequently, this modified uracil was reacted with protected 2-deoxyribose in the presence of SnCl4. Finally, protected α- and β-anomers 111 and 109 were treated with methanolic sodium methoxide to afford the nucleosides 112 and 110. Synthesis of

Stereoselective synthesis of four possible isomers of streptopyrrolidine

• Debendra K. Mohapatra,
• Barla Thirupathi,
• Pragna P. Das and
• Jhillu S. Yadav

Beilstein J. Org. Chem. 2011, 7, 34–39, doi:10.3762/bjoc.7.6

• investigated (SnCl4, BF3·OEt2, ZnI2, TiCl4, EtOAc/LDA/ZnBr2) BF3·OEt2 gave excellent selectivity (exclusively 8b) (Table 1). Following a modification of the Mosher method [32][33], the newly created stereogenic center in compound 8b bearing the hydroxyl group was assigned. The syntheses of both the (S)- and (R

• , 0.8 mmol) in CH2Cl2 (5 mL) under a nitrogen atmosphere and cooled to −78 °C, was added 1 M solution of SnCl4 in CH2Cl2 (0.1 mL, 0.81 mmol). After 10 min, (1-ethoxyvinyloxy)trimethylsilane (0.26 g, 1.6 mmol) was added at the same temperature. The reaction mixture was stirred for 1 h at −78 °C. After

• ) SnCl4, (1-ethoxyvinyloxy)trimethylsilane, CH2Cl2, −78 °C, 2 h, 70% (8a:8b = 3:7); (d) LDA, EtOAc, ZnBr2, −78 °C, 1 h, 82%, (8a:8b = 95:5). Reagents and conditions: (a) (1) TFA, CH2Cl2, rt, 4 h; (2) Zr(OtBu)4, HOAt, toluene, 60 °C, 12 h, 82% over two steps. Addition reaction under different conditions to

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• -isomers [87]. Unlike pyrroles, furan, thiophene and selenophene react with CF3SCl only in the presence of catalysts. For selenophene [84] and thiophenes [85] SnCl4 is sufficient, whilst furans require more forcing conditions usually involving prolonged heating (20 h at 60 °C) and in pyridine for

Preparation of aminoethyl glycosides for glycoconjugation

• Robert Šardzík,
• Gavin T. Noble,
• Martin J. Weissenborn,
• Andrew Martin,
• Simon J. Webb and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2010, 6, 699–703, doi:10.3762/bjoc.6.81

• fucoside 14 was generated both from the acetate and bromide. Higher alpha selectivity was observed with the bromide (α/β ratio of crude product 82:18). N-Acetylglucosamine 15 was successfully prepared from the β-acetate using SnCl4 (method D). When starting from the α-acetate, no reaction was observed and

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

• many other Lewis acids including BF3, BeCl2, TiCl4, SbCl5 or SnCl4 have been described as catalysts for the FC alkylation. Furthermore, strong Brønsted-acids including sulfuric acid, hydrofluoric acid or super acids such as HF•SbF5 and HSO3F•SbF5 have also been shown to accelerate this transformation

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

• allylsilane 285 mediated by SnCl4 afforded the bis-THF 286. Finally, the butenolide ring was installed using a procedure developed by Marshall’s group [96] to provide synthetic (+)-asimicin. In 2006, Marshall’s group reported the total synthesis of asimicin by a highly convergent route in which Grubbs cross

Synthesis of thienyl analogues of PCBM and investigation of morphology of mixtures in P3HT

• Fukashi Matsumoto,
• Kazuyuki Moriwaki,
• Yuko Takao and
• Toshinobu Ohno

Beilstein J. Org. Chem. 2008, 4, No. 33, doi:10.3762/bjoc.4.33

• procedure [22], as shown in Scheme 1. First, benzo[b]thiophene and thieno[3,2-b]thiophenes were acylated by using SnCl4; the acylation was performed at low temperature as a safeguard against the high reactivity of the thienyl groups (yields: 1a; 15%, 1b; 46%, 1c; 74%, 1d; 33%). Glutaric acid monomethyl

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• appropriate amine (PMBNH2 or BnNH2 respectively) with ethyl E-4-chloro-3-methoxybut-2-enoate.[11] Reaction of 4b with n-BuLi as before followed by TMSCl to generate 5b, and reaction with aldehyde 7 (0.7 equiv) as limiting reagent using SnCl4 (2 equiv) as the Lewis-acid promoter with rapid stirring of the

• standard conditions of (Boc)2O/DMAP and NaH/CBzCl respectively. Each was independently subjected to our in situ Mukaiyama sequence involving n-BuLi followed by TMSCl, and then addition of aldehyde 7 and SnCl4. However, following the normal work-up, tlc analysis in each case revealed consumption of starting

• 16. Structure of 6a with numbering to demonstrate numbering system used in this section. An example of a vinylogous Mukaiyama aldol in a natural product synthesis. Reagents and conditions: a) RCHO 2, SnCl4 (1.2 equiv), ether, -85°C. Our vinylogous Mukaiyama aldol reaction with different substituents

High stereoselectivity on low temperature Diels- Alder reactions

• Luiz Carlos da Silva Filho,
• Valdemar Lacerda Júnior,
• Mauricio Gomes Constantino,
• Gil Valdo José da Silva and
• Paulo Roberto Invernize

Beilstein J. Org. Chem. 2005, 1, No. 14, doi:10.1186/1860-5397-1-14

• eluent. Diels-Alder reactions of 2-cycloenones 1 – 6 with cyclopentadiene catalyzed by NbCl5. Comparison between Diels-Alder reactions of 2-cycloenones with cyclopentadiene catalyzed by NbCl5, AlCl3 [1] and SnCl4 [18]. Supporting Information Supporting Information File 17: Contains general methods (S2