Stereoselective sequential photochemical cycloaddition - iminium ion - propargylsilane cyclization. Synthesis of quinolizidines and pyrido [1,2-a]azepines
摘要:
Photochemical cycloaddition of the enaminecarbaldehydes 15 and 16 with the acrylic acid derivatives 20a-c gave the 2-hydroxytetrahydropyridines 21a-c and 24a-c, respectively which cyclize on treatment with trifluoroacetic acid or Lewis acids to furnish the quinolizidines 22a-c and pyrido[1,2-a]azepines 25a-c, respectively in good yields and with high 1,3-induced diastereoselectivity. Indolizidines 27 cannot be prepared by this method.
Intramolecular reactions of 2-propynylsilanes with n-acyliminium ions
作者:Wim J. Klaver、Marinus J. Moolenaar、Henk Hiemstra、W.Nico Speckamp
DOI:10.1016/s0040-4020(01)86638-2
日期:1988.1
precursors lead to bridged azabicyclic systems 34–45 (Table I), containing the uncommon α-allenic amide functionality. After introduction of a tert-butoxycarbonyl or a tosyl group onto the lactam nitrogen atom, these molecules react with cuprates in an SN2' fashion. The products 52–58 (Table II) are angularly functionalized trans-fused carbobicycles containing a 1,3-diene moiety.
2-丙炔基硅烷与环状N-酰基亚胺离子前体的分子内酸辅助反应会导致桥连的氮杂双环体系34 – 45(表I),其中含有罕见的α-烯丙基酰胺官能团。在内酰胺氮原子上引入叔丁氧基羰基或甲苯磺酰基后,这些分子以S N 2'的方式与铜酸盐反应。产物52 – 58(表II)是含有1,3-二烯部分的有角度官能化的反式融合碳环。
Diastereoselective alkylation of the dianion of 5-ethoxy-4(S)-hydroxy-1-isopropyl-2-pyrrolidinone; Synthesis of enantiomerically pure azabicycles
作者:Wim J. Klaver、Henk Hiemstra、W.Nico Speckamp
DOI:10.1016/s0040-4039(01)81047-9
日期:1987.1
The alkylation of the dianion of the title compound () readily prepared from (S)-malic acid, with ω-iodo-1-trimethylsilyl-2-alkynes (-) occurs with high trans-selectivity with respect to the hydroxyl function. The products (-) cyclize in formic acid to enantiomerically pure azabicyclic allenes (-), one of which () might be a suitable precursor to peduncularine ().