Unexpected Hydrogenation of C?C-Double Bonds withtert-Butyl Iodide
摘要:
Heating of 3-isobutylidene-2,5-diketopiperazines 1 or 4, maleinimide or 2,3-dichloro-5,6-dicyano-p-benzoquinone with tert-butyl iodide in toluene gave rise to hydrogenation of the conjugated C-C-double bond affording 3-isobutyldiketopiperazines 2(rac) and 3(rac), succinimide, or 2,3-dichloro-5,6-dicyanohydroquinone, respectively. Furthermore, an interesting N-O-migration of a benzoyl group as well as reductive aromatization to pyrazines 5 and 6, respectively, were observed.
Stereoselective Epoxidation and Bromoalkoxylation with 3-Ylidenepyrazine-2,5-diones
作者:Jürgen Liebscher、Annett Bartels、Peter G. Jones
DOI:10.1055/s-2003-36259
日期:——
were stereoselectively epoxidsed by dimethyldioxirane giving access to spirooxiranes 2 and diols 3. Bromohydroxylation and bromoalkoxylation of 3-ylidenepyrazine-2,5-diones 1 produced high yields of opticallyactive3-(1-bromoalkyl)pyrazine-2,5-diones 4 with a 3-hydroxy or 3-alkoxy function, respectively. Whereas direct hydrogenation of epoxides 2 afforded epimeric mixtures of 3-( 1-hydroxyalkyl)pyrazine-2
Enantiomerically pure pyruvate derivatives by epoxidation of ylidenediketopiperazines
作者:Annett Bartels、Peter G. Jones、Jürgen Liebscher
DOI:10.1016/0040-4039(95)00600-h
日期:1995.5
Reaction of 3-ylidene-2,5-diketopiperazines 1 with 3,3-dimethyldioxirane (2) gives enantiomerically pure spiro-annelated epoxides 3, which are chiral pyruvate derivatives.
Intermolecular and Intramolecular Diels−Alder Cycloadditions of 3-Ylidenepiperazine-2,5-diones and 5-Acyloxy-2(1<i>H</i>)-pyrazinones
作者:Shangde Jin、Pablo Wessig、Jürgen Liebscher
DOI:10.1021/jo0100897
日期:2001.6.1
Diels-Alder reactions of alkenes and alkynes to the piperazine ring, under acidic conditions or in the presence of acetyl chloride, to afford tricyclic piperazine-2,5-diones 19, 20, 23-25, 27, 44, and 45. Intramolecular cycloadditions occur if 3-ylidenepiperazine-2,5-diones 30 and 32 are used as the starting materials. This procedure is a convenient path to bridged bicyclo[2.2.2]diazaoctane ring systems such
Unexpected Hydrogenation of C?C-Double Bonds withtert-Butyl Iodide
作者:Shangde Jin、J�rgen Liebscher
DOI:10.1002/prac.19983400415
日期:——
Heating of 3-isobutylidene-2,5-diketopiperazines 1 or 4, maleinimide or 2,3-dichloro-5,6-dicyano-p-benzoquinone with tert-butyl iodide in toluene gave rise to hydrogenation of the conjugated C-C-double bond affording 3-isobutyldiketopiperazines 2(rac) and 3(rac), succinimide, or 2,3-dichloro-5,6-dicyanohydroquinone, respectively. Furthermore, an interesting N-O-migration of a benzoyl group as well as reductive aromatization to pyrazines 5 and 6, respectively, were observed.