Asymmetric synthesis via aziridinium ions: exploring the stereospecificity of the ring opening of aziridinium ions and a formal synthesis of (−)-swainsonine

Revisiting the sparteine surrogate: development of a resolution route to the (−)-sparteine surrogate

“…Thus, although the yields were higher than in acetonitrile (12%; Table 1, entry 10), the ers were not as high as that in acetonitrile (97 : 3 er). As a result, our attention focused on investigating two co-solvents with acetonitrile (entries [16][17][18][19][20]. Use of water as the co-solvent completely suppressed the crystallisation process and no solid formation was seen (entries [16][17][18].…”

“…2 Examples include lithiation α to nitrogen, 1,3-7 oxygen 1,8-10 and phosphorus, 11,12 benzylic lithiation-trapping, 8,13 Pd(II)-mediated alcohol oxidation, 1,8 Cu(II)-mediated resolution of racemic BINOL and VAPOL, 8,14 ortholithiation 15 and carbolithiation. 8,16 In terms of synthetic applications, the (+)-sparteine surrogate (+)-1 has been utilised in a range of natural product syntheses including (−)-kainic acid, 17,18 (−)-amurensinine, 19 (−)-swainsonine, 20 (−)-decarestrictine D, 21 (S)-nicotine, 22 (+)-sclerotiorin, 23 (+)-erogorgiaene, 24 (+)-giganin 25 and (−)-hygroline. 26 In each case, (+)-1 was required to deliver the naturally occurring configuration.…”

Synthesis of Secondary Metabolites from Higher Fungi

“…Three transition-metal-catalysed reactions have been applied to the synthesis of 87: in 2002 ruthenium was used by Blechert and co-workers, 101 while gold was employed by Bates and co-workers in 2009 102 and palladium by the same group in 2011. 103 In 2008 Kang and coworkers developed a chromium-salen-catalysed iodocyclisation, 104 followed in 2010 by an aziridinium ion ring opening, outlined by O'Brien and co-workers, 105 an allenylmetal addition, involving sulfinylimides as intermediates, established by a French group in 2011, 106 and a method by Wardrop and Bowen using acylnitrenium ions in 2011. 107 Due to the large number of syntheses of 87 and the plethora of reactions used, it is impossible to discuss them all in detail.…”

Recent advances in the synthesis of naturally occurring pyrrolidines, pyrrolizidines and indolizidine alkaloids using proline as a unique chiral synthon

“…111) and successfully utilised by O'Brien's group. 112 The commercially available proline was converted to trityl ester 373 which on LAH reduction followed by Swern oxidation afforded the aldehyde 374. The diastereoselective addition of vinylmagnesium chloride to the aldehyde 374 afforded the hydroxyl derivative 375 diastereoselectively (98 : 2).…”