A rapid assembly of homochiral 2,3,4-trisubstituted pyrrolidines
摘要:
The intramolecular 1,3-dipolar cycloaddition of homochiral dihydroimidazolium ylides, generated in situ, is the key reaction in a sequence that rapidly affords optically active 2,3,4-trisubstituted pyrrolidines suitably functionalised for further elaboration. (C) 1997 Elsevier Science Ltd.
Cycloaddition of homochiral dihydroimidazoles: A 1,3-dipolar cycloaddition route to optically active pyrrolo[1,2-a]imidazoles
作者:Raymond C. F. Jones、Kevin J. Howard、John S. Snaith、Alexander J. Blake、Wang-Shei Li、Peter J. Steel
DOI:10.1039/c0ob00529k
日期:——
terminating in a 1,3-dipolarcycloadditionreaction that affords optically active pyrrolo[1,2-a]imidazoles. Three bonds of the so-formed pyrrolidine moiety are constructed in this cascade. The cycloaddition follows an endo approach of dipole and dipolarophile with anti geometry of the dipole and facial selectivity derived from the phenyl substituent. Inter- and intramolecularcycloaddition modes are observed
N-光学活性的烷基化1-苄基-4-苯基-4,5-二氢咪唑活性烷基卤化物和在一系列缺电子的烯烃双极性亲和剂存在下用DBU处理如此形成的4,5-二氢咪唑鎓离子,构成终止于1,3-偶极环加成反应的``一锅''级联反应提供光学活性的吡咯并[1,2- a ]咪唑。在该级联反应中构建了如此形成的吡咯烷部分的三个键。环加成遵循内偶极子和亲偶极与方法抗偶极子的几何形状,并从苯基取代基衍生的面部选择性。观察到分子间和分子内的环加成模式。
A Versatile Cascade of Intramolecular Vilsmeier−Haack and Azomethine Ylide 1,3-Dipolar Cycloaddition toward Tricyclic Cores of Alkaloids
作者:François Lévesque、Guillaume Bélanger
DOI:10.1021/ol802010n
日期:2008.11.6
In the pursuit of synthetic efficiency, we developed an innovative one-pot transformation of linear substrates into bi- and tricyclic adducts using a cascade of amide activation, nucleophilic cyclization, azomethine ylide generation, and subsequent inter- or intramolecular 1,3-dipolar cycloaddition. Despite the high density and variety of functional groups on the substrates, the sequence occurred with perfect chemoselectivity with good to excellent yields.
A rapid assembly of homochiral 2,3,4-trisubstituted pyrrolidines
作者:Raymond C.F. Jones、Kevin J Howard、John S Snaith
DOI:10.1016/s0040-4039(97)00111-1
日期:1997.3
The intramolecular 1,3-dipolar cycloaddition of homochiral dihydroimidazolium ylides, generated in situ, is the key reaction in a sequence that rapidly affords optically active 2,3,4-trisubstituted pyrrolidines suitably functionalised for further elaboration. (C) 1997 Elsevier Science Ltd.
Annulation of dihydroimidazoles: a 1,3-dipolar cycloaddition route to pyrrolo[1,2-a]imidazoles, pyrrolidines and pyrroles
作者:Raymond C. F. Jones、Kevin J. Howard、John R. Nichols、John S. Snaith
DOI:10.1039/a802048e
日期:——
4,5-Dihydroimidazolium ylides, formed by N-alkylation of 4,5-dihydroimidazoles, undergo diastereoselective endo 1,3-dipolar cycloaddition with electron-deficient alkene dipolarophiles to afford hexahydropyrrolo[1,2-a]imidazoles; reduction of the aminal functionality in the cycloadducts leads to substituted pyrrolidines. Cycloaddition using 2-chloropropenonitrile, followed by base treatment, affords pyrroles.