Knorr- Rabe partial reduction of pyrroles: Application to the synthesis of indolizidine alkaloids

• Brendon S. Gourlay,
• John H. Ryan and
• Jason A. Smith

Beilstein J. Org. Chem. 2008, 4, No. 3, doi:10.1186/1860-5397-4-3

• Brendon S. Gourlay John H. Ryan Jason A. Smith School of Chemistry, University of Tasmania, Hobart, Australia CSIRO Division of Molecular and Health Technologies, Bag 10, Clayton South, Victoria, Australia 10.1186/1860-5397-4-3 Abstract Background The Birch reduction of electron rich pyrroles

• rich pyrroles. Results The partial reduction of bicyclic α-ketopyrrole derivatives has been performed under dissolving metal conditions with zinc and hydrochloric acid to give excellent yields of hexahydroindolizidines. This reduction method has been utilised for the diastereoselective synthesis of 5

• electron density of these aromatic heterocycles inhibits the addition of an electron, the first step of a Birch reaction [2]. Donohoe has shown that the partial reduction of pyrroles is possible but this process generally requires the presence of at least two electron withdrawing groups that reduce the

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

• resulted in us developing a one-pot methodology involving its in situ generation. We have recently demonstrated the applicability of N-protected-4-methoxy-2-trimethylsilyloxy pyrroles 5 to the synthesis of key intermediates for the alkaloids lepadiformine [10] and castanospermine [11] using vinylogous

Aroylketene dithioacetal chemistry: facile synthesis of 4-aroyl- 3-methylsulfanyl- 2-tosylpyrroles from aroylketene dithioacetals and TosMIC

• H. Surya Prakash Rao and
• S. Sivakumar

Beilstein J. Org. Chem. 2007, 3, No. 31, doi:10.1186/1860-5397-3-31

• hydride in THF at rt resulted in a facile synthesis of the 4-aroyl-3-methylsulfanyl-2-tosylpyrroles 3 in good yield along with a minor amount of 4-[(4-methylphenyl)sulfonyl]-1-[(methylsulfanyl)methyl]-1H-imidazole 4. This study lead to the synthesis of 2,3,4-trisubstiuted pyrroles having 1-naphthoyl/2

• could lead to 2,3,4-trisubstituted pyrroles having an aroyl moiety located on C-4. Von Leusen's and others have amply demonstrated that the cycloaddition of TosMIC to the alkenes having strong electron-withdrawing groups (Michael acceptors) followed by loss of TosOH provide 3,4-disubstituted pyrroles in

• excellent yield. [8][9][10] Similarly, the reaction of TosMIC with activated alkynes afford trisubstituted pyrroles. However, the scope of pyrrole synthesis via cycloaddition of TosMIC to the "push-pull" alkenes is not well explored. We reasoned that, in the event of cycloaddition taking place between