@article{7576c65263a54188be86dd70af827d81,
title = "Chiral acetylenic sulfoxide in alkaloid synthesis. Total synthesis of (R)-(+)-carnegine.",
abstract = "Remarkable diastereoselectivity was observed in the cyclization of β-aminovinyl sulfoxide 5a prepared from chiral acetylenic sulfoxide 1a in acidic medium. The cyclized product 6a was then converted to (R)-(+)-carnegine.",
author = "Lee, {Albert W.} and Chan, {W. H.} and Lee, {Yu Kai}",
note = "Funding Information: Finally, 6a was transformed to (R)-(+)-camegine with the following procedures (Scheme II): reductive methylation of 6a with sodium cyanoborohydridea nd aqueousf ormaldehyde in acetonitrilelu yielded 8a [lHNMR (250 MHz)(CDCl3): 6 8.42 (dd, J= 1.40, 7.89 Hz, lH), 8.28 (dd, J= 1.14, 8.13 Hz, lH), 8.00-7.94 (m, lH), 7.71-7.64 (m, IH), 6.5Q (s, lH), 6.53 (s, lH), 4.23 (dd, J= 4.07, 11.91 Hz, lH), 3.83 (s, 3H), 3.79 ( s, 3H), 3.62 (t, J= 12.3Q, lH), 3.54-3.43 (m, lH), 3.17-2.96 (m, 2H), 2.82 (dd, J= 4.12, 12.82, lH), 2.66 (s, 3H), 2.47-2.39 (tn. 1H); MS 219.1253 (M+ - o-N0&$I4SOH found), 219.1259 (M+ - o-N02C6H4SOH talc.)*; [a]2$ = +256.7o( c 0.24, chloroform); m.p. = 174-176oC (decomp.)]. From NMR and TLC, once again there was no trace sign of the existence of the corresponding diastereomer.D esulfurization of 8a with excess Raney Nickel in water saturatede therI yielded (R)-(+)-camegine [ [c1126~= +27.6o( c 0.15, ethanol); lit. lk [a]lgD = +23.4o( c 0.15, ethanol)] as a viscous oil, which the spectroscopicd atawere identical with thoser eportedi n literatures.l2 In sumrruaryt,h e chiral acetylenic sulfoxide la had shown to be a versatile two-carbon syntbon for the asymmetric synthesis of the tetrahydroiscquinolinea lkaloid with high diastereoselectivitya t the C-l position. Further elaborationo f the key intermediate6 a to other tetrabydroisquinolinea lkaloids and the use of o-nitrophenyl sulfinyl group in organic synthesesa re in progress. Acknowledgements: Finanical support from he UPGC (RX-89/90-13) and FRCi (88/89-n-05) granti s gratefully acknownledged.W e would also like to thank the Chemistry Departmento f the Chinese University of Hong Kong and University of HongXoni; for providing some of the spectroscopics ervices.",
year = "1991",
month = nov,
day = "18",
doi = "10.1016/0040-4039(91)80426-7",
language = "English",
volume = "32",
pages = "6861--6864",
journal = "Tetrahedron Letters",
issn = "0040-4039",
publisher = "Elsevier Ltd.",
number = "47",
}