Download Selectivity in the Synthesis of Cyclic Sulfonamides: by Kimberly Geoghegan PDF

By Kimberly Geoghegan

In the world of natural chemistry one significant problem we're presently confronted with is find out how to gather possibly worthwhile molecules in new ways in which generate molecular complexity and in sequences which are as effective as attainable. Our efforts during this regard, particularly for the practise of amino containing compounds incorporating an fragrant ring, are defined during this doctoral thesis. We found an attractive regioselectivity in an intramolecular Heck response, which we studied for a sequence of substrates which are impartial when it comes to the dimensions of the newly shaped ring, the place very excessive degrees of selectivity when it comes to the recent carbon-carbon bond are usually saw. DFT calculations have been played to try to make clear the response series. This regioselective Heck response, mixed with the reductive removing of the transitority amino-protecting crew, allowed us to synthesize the Sceletium alkaloids: mesembrane, mesembranol and mesembrine.

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Additional info for Selectivity in the Synthesis of Cyclic Sulfonamides: Application in the Synthesis of Natural Products

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7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. Heck RF, Nolley JPJ (1972) J Org Chem 37:2320 Mizoroki T, Mori K, Ozaki A (1971) Bull Chem Soc Jpn 44:581 Heck RF (1982) Org React 27:345 Gibson SE, Middleton RJ (1996) Contemp Org Synth 3:447 Link JT (2002) Org React 60:157 Zeni G, Larock RC (2006) Chem Rev 106:4644 Knowles JP, Whiting A (2007) Org Biomol Chem 5:31 Phan NTS, Van Der Sluys M, Jones CW (2006) Adv Synth Catal 348:609 Oestreich M (ed) (2009) The Mizoroki-Heck reaction.

18. This strategy allows us to perform electrophilic aromatic substitution at the ortho-positions by first blocking the para-position. The reaction of anisole with t-butanol in the presence of Lewis acid AlCl3 afforded the 1,4-disubstituted benzene 146 in a moderate 44 % isolated yield. ), PhMe, 60 °C, 24 h, quant. 4 Regioselectivity in the Intramolecular Heck Reaction of Sulfonamides 29 crude sulfonyl chloride 147 (one isomer detected in the 1H NMR spectra), which was treated with excess ammonium hydroxide in MeCN to furnish sulfonamide 148 in an excellent 96 % isolated yield.

10 ppm Fig. 2 NOe studies of compounds 211–213 yield respectively. Relative stereochemistry of the three compounds was assigned using COSY and nOe NMR studies, represented in Fig. 2. The cis-relationship between the two bromine atoms of compound 213 was reasoned due to a strong correlation between protons 3-H and 4-H, which could be observed in the 2-D nOe spectrum (Fig. 2). More evidence to support this was the absence of a correlation between protons 3-H and 4-H with the bridgehead protons 10-HA/10-HB, suggesting the stereochemistry of compound 213 might resemble that depicted in Fig.

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