Asymmetric desymmetrization of pseudo-meso 5-hydroxy-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-ones
作者:Namakkal G Ramesh、Frank J.A.D Bakkeren、Debby de Groot、Umberto Passamonti、Antonius J.H Klunder、Binne Zwanenburg
DOI:10.1016/s0040-4020(01)01007-9
日期:2001.12
-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one. Desymmetrization using (S)-prolinol or its methyl ether leads to the corresponding enaminones in high yields and with a de of 50%. Complete separation of the diastereomers has been conveniently achieved via their acetates. The absolute stereochemistry of the major diastereomer was determined by single-crystal X-ray diffraction analysis. Reductive elimination
An effective regioselective electrophilic halogenation of tricyclo[5.2.1.02,6]decenyl enaminones
作者:Namakkal G. Ramesh、Erik H. Heijne、Antonius J.H. Klunder、Binne Zwanenburg
DOI:10.1016/s0040-4039(98)00474-2
日期:1998.5
4 undergo a surprisingly effective regioselective halogenation using N-halosuccinimides (NXS) under electrophilic conditions. Exclusive α-halogenation is observed using one equiv. of NXS, whereas, either α,γ- or α,N-bishalogenation products are formed in quantitative yields when an additional equiv. of NXS is applied. Most importantly, halogenation of the C8C9 norbornene bond is not observed.
作者:René de Gelder、Jan M. M. Smits、Namakkal G. Ramesh、Frank J. A. D. Bakkeren、Debby de Groot、Antonius J. H. Klunder
DOI:10.1023/a:1021733108852
日期:——
The crystal and molecular structure of (+)-(1R, 2S, 6R, 7S, 1'R)-5-(1'-phenylethylamino)endo-tricyclo[5.2.1.0(2,6)]deca-4,8-dien-3-one is described. Based on the known absolute configuration (R) of the alpha-phenylethylamine moiety the X-ray analysis revealed the absolute configuration of the title compound. The structure was refined to R-1 = 0.0298 for 1950 reflections (with I > 2 sigma(I)). Crystal data: C18H19NO, monoclinic, space group P2(1), a = 6.7406(4), b = 9.959(2), c = 11.3123(8)Angstrom, beta = 102.969(5), V = 740.0(2)Angstrom(3), and Z = 2.
Enantioselective synthesis of 4-aminocyclopent-2-ene-1-one from tricyclo[5.2.1.02,6]decenyl enaminones
作者:Namakkal G. Ramesh、Antonius J.H. Klunder、Binne Zwanenburg
DOI:10.1016/s0040-4039(97)10820-6
日期:1998.3
An efficient enantioselective synthesis of 4-amino-cyclopent-2-ene-1-one 12 from enaminones 8 and and its diastereomer has been accomplished via a one step electron transfer reduction of the enaminone double bond and concomitant removal of an alpha-methylbenzyl group, followed by a [4 + 2] cycloreversion strategy. (C) 1998 Elsevier Science Ltd. All rights reserved.