An approach to chiral η4-butadiene-Fe(CO)3 complexes via diastereoselective complexation of nonracemic 2-alkoxy-4-vinyl-2,5-dihydrofuran derivatives
作者:Hans-Günther Schmalz、Erik Heßler、Jan W. Bats、Gerd Dürner
DOI:10.1016/s0040-4039(00)60723-2
日期:1994.6
Complexation of (+)-L-arabinose-derived 2-benzyloxy-4-vinyl-2,5-dihydrofuran derivatives (8) with Fe2(CO)9 in ether proceeds diastereoselectively providing a (separable) mixture of the corresponding exo- and endo-η4-diene-Fe(CO)3complexes 9 and 10 in a ratio of about 1 : 3. The relative (and absolute) configuration of the complexation products was determined by a combination of analytical methods
Total synthesis of the lignans (-)- and (+)-burseran, (-)-cubebin, and (-)-hinokinin by diastereoselective conjugate addition of benzyl anions to 2-(R) and (s)-benzyloxy-2,5-dihydro-4-(3,4-methylenedioxybenzoyzfuran
作者:Nicola Rehnberg、Göran Magnusson
DOI:10.1016/0040-4039(88)85304-8
日期:1988.1
1,2-Addition of 3,4-methylenedioxymagnesium bromide to 2-(R) and (S)-benzyloxy-2,5-dihydro-4-furancarboxaldehyde, followed by oxidation, gave the title ketones (3r and 3s). Conjugate addition of the anions of 3,4,5-trimethoxy- and 3,4-methylenedioxybenzaldehyde diphenylthioacetal to 3r and 3s and Raney-nickel desulfurisation, followed by hydrogenolysis under various conditions, gave the title lignans
Diastereoselective conjugate addition of lithium methylcyanocuprate to the chiral isoprene units 2-(R)- and (S)-benzyloxy-2,5-dihydro-4-furancarbox-aldehyde. Total synthesis of (−)- and (+)-botryodiplodin and (+)- and (−)-epibotryodiplodin.
作者:Nicola Rehnberg、Torbjörn Frejd、Göran Magnusson
DOI:10.1016/s0040-4039(00)95543-6
日期:1987.1
Conjugateaddition of lithium methylcyanocuprate to the titlealdehydes proceeded with high diastereoselectivity (d.e. 94%). Methyl lithium 1,2-addition, followed by Swern oxidation of the resultingalcohols, gave benzyl botryodiplodin and benzyl epi-botryodiplodin.Hydrogenolysis of the benzyl groups gave the enantiomeric pairs ofbotryodiplodin 10r and 10s and epi-botryodiplodin (9r and 9s).
General conjugate-addition method for the synthesis of enantiomerically pure lignans. Total synthesis of (-)- and (+)-burseran, (-)-dehydroxycubebin, (-)-trichostin, (-)-cubebin, (-)-5''-methoxyhinokinin, and (-)-hinokinin
作者:Nicola Rehnberg、Goeran Magnusson
DOI:10.1021/jo00301a026
日期:1990.7
Chiral aldehydes by ring contraction of pento- and hexopyranoside epoxides