Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• set up the desired stereochemistry at C-8 and C-8a. Epimerisation of the ester in the reduced compound (−)-20 produced (−)-21, reduction of which gave the alcohol (−)-22. Reduction of the corresponding methanesulfonate with lithium triethylborohydride, as described by Holmes et al. [24], completed the

• ]. Finally, since the pendent substituents in the indolizidine series can be induced to adopt a trans-orientation by base-catalysed epimerisation of a carbonyl substituent adjacent to the bridgehead position (cf Scheme 1), it should in principle be possible to effect a similar epimerisation in the

Pd-catalysed [3 + 3] annelations in the stereoselective synthesis of indolizidines

• Olivier Y. Provoost,
• Andrew J. Hazelwood and
• Joseph P. A. Harrity

Beilstein J. Org. Chem. 2007, 3, No. 8, doi:10.1186/1860-5397-3-8

• corresponding Mosher's ester showed a single resonance in the 19F NMR spectrum (235 MHz, CDCl3: δ-72.0) suggesting that minimal epimerisation had taken place during the oxidation process. We next decided to investigate the formation of the azabicycle via the deprotection of the Ts-amine moiety followed by

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

• temperature, allowing further reduction to the corresponding primary alcohols. Fortunately, the two alcohol products could be oxidised to the desired aldehydes syn-4a and anti-4a, using Dess-Martin periodinane[22][23] without epimerisation of the α-stereogenic centre (Scheme 7). With all four cyclisation