A convenient allylsilane- N-acyliminium route toward indolizidine and quinolizidine alkaloids

• Roland Remuson

Beilstein J. Org. Chem. 2007, 3, No. 32, doi:10.1186/1860-5397-3-32

• with one equivalent of stannic chloride resulted in the formation of 10 via the acyliminium ion intermediate 11. Subsequent oxidation of alcohol 10 with pyridinium dichromate, then catalytic hydrogenation (H2 over Pd/C) of ketone 12 induced hydrogenolysis of the CBz group, reduction of the double bond

• of 15 with stannous chloride led to compounds 17a and 17b. The next two steps were straightforward: oxidation (pyridinium dichromate) of 17a and 17b afforded α,β-ethylenic ketones 18a and 18b. On hydrogenation over palladium on carbon, 18a gave a mixture of indolizidines 19 and 20 which were

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• . [7][8][9][10][11][12][13][14][15][16][17] It is well known that the substituted pyridinium cations are good electron acceptors. [18] Garcia and coworkers have used N-alkyl-2,4,6-triphenylpyridinium tetrafluoroborate as photosensitizer in the photochemical cyclization of 5-methyl-4-hexenoic acid to

An efficient synthesis of tetramic acid derivatives with extended conjugation from L-Ascorbic Acid

• Biswajit K. Singh,
• Surendra S. Bisht and
• Rama P. Tripathi

Beilstein J. Org. Chem. 2006, 2, No. 24, doi:10.1186/1860-5397-2-24

• . In continuation of this work, we have synthesised dienyl tetramic acid derivatives. Results 5,6-O-Isopropylidene-ascorbic acid on reaction with DBU led to the formation of tetronolactonyl allyl alcohol, which on oxidation with pyridinium chlorochromate gave the respective tetranolactonyl allylic

The vicinal difluoro motif: The synthesis and conformation of erythro- and threo- diastereoisomers of 1,2-difluorodiphenylethanes, 2,3-difluorosuccinic acids and their derivatives

• David O'Hagan,
• Henry S. Rzepa,
• Martin Schüler and
• Alexandra M. Z. Slawin

Beilstein J. Org. Chem. 2006, 2, No. 19, doi:10.1186/1860-5397-2-19

• ]. Halofluorination of electron-rich alkenes with in situ fluoride displacement generates vicinal difluoro products. PPHF is Olah's reagent, pyridinium poly(hydrogen fluoride) [15]. Bromofluorination of stilbene [19]. Treatment of anti-14 with base generated the E-fluorostilbene 15 by an anti elimination mechanism

Efficient synthesis of 5-substituted 2-aryl- 6-cyanoindolizines via nucleophilic substitution reactions

• Eugene V. Babaev,
• Natalya I. Vasilevich and
• Anna S. Ivushkina

Beilstein J. Org. Chem. 2005, 1, No. 9, doi:10.1186/1860-5397-1-9

• products in good yields.[3] An interesting method for preparing 5-substitutied indolizines by recyclization of oxazolo[3,2-a]pyridinium salts was developed in our laboratory.[4][5] Using this strategy a series of 5-substituted indolizines have been prepared in good yields, but (although the method seems to