The first regiodivergent opening of unbiased epoxides providing the ring-opened products in high enantiomeric excess from racemic and exceptionally high enantiomeric excess from enantioenriched substrates in a double asymmetric process has been devised. It constitutes a more general case of the very important enantioselective openings of meso-epoxides.
Base-mediated intramolecular one-pot double-cyclization of epoxide-tethered 2-fluorobenzenesulfonamides: an avenue to 1,4-benzoxazine-fused benzothiaoxazepine-1,1-dioxides
作者:Jonali Das、Biraj Jyoti Borah、Sajal Kumar Das
DOI:10.1039/c9ob02377a
日期:——
A regio- and diastereoselective synthesis of pharmaceutically relevant 1,4-benzoxazine-fused benzothiaoxazepine-1,1-dioxides has been achieved under transition metal-free mild reaction conditions.
Switching of regioselectivity in base-mediated diastereoselective annulation of 2,3-epoxy tosylates and their <i>N</i>-tosylaziridine analogs with 2-mercaptobenzimidazole
作者:Arup Jyoti Das、Hemi Borgohain、Bipul Sarma、Sajal Kumar Das
DOI:10.1039/c9ob02454a
日期:——
intermolecular alkylation followed by an N-C3 bond-forming, endo-selective intramolecular epoxide ring-opening cyclization reaction. A spectacular regioselectivity switching (tandem S-C3 and N-C1 bond formation reactions) was observed with related trans-N-tosylaziridine substrates. Wide substrate scope, complete diastereoselectivity, high to complete regioselectivity and mild transition metal-free conditions
DIASTEREOSELECTIVE OXIDATION OF 2,3-EPOXY ALCOHOL-DERIVED THIIRANES, AND <sup>1</sup>H NMR ANALYSIS OF THE CORRESPONDING THIIRANE S-OXIDES
作者:Paul R. Carlier、Guilan Liu、H. Y. Peter Lam
DOI:10.1080/10426509708043562
日期:1997.7.1
alcohol-derived thiiranes; steric factors alone appear to determine the anti:syn selectivity. Detailed 1H NMR analysis was performed on both the stable anti- and the unstable syn-thiirane S-oxides. The thiirane S-oxide ringprotons are found to possess unusuallylargevicinalcouplingconstants (approx. 11 Hz) and their chemical shifts are quite sensitive to the anisotropy of the SO moiety.
摘要 制备了衍生自 cis-2,3-epoxyhexan-1-ol 的抗硫杂环丙烷 S-氧化物,用作烯烃环氧化和单线态氧化的过渡态类似物。发现通常在硫化物氧化中利用的 β-羟基导向效应在导向顺式环氧醇衍生的硫杂丙环的氧化方面完全无效;空间因素似乎单独决定了抗:syn 选择性。对稳定的抗和不稳定的合成硫杂丙环硫醚 S-氧化物进行了详细的 1 H NMR 分析。发现硫杂环 S-氧化物环质子具有异常大的邻位耦合常数(约 11 Hz),并且它们的化学位移对 SO 部分的各向异性非常敏感。
An epoxide-opening cyclization/double Smiles rearrangement cascade approach to <i>N</i>-aryl-1,4-benzoxazines and <i>N</i>-arylindolines
作者:Jonali Das、Abhijit Gogoi、Biraj Jyoti Borah、Sajal Kumar Das
DOI:10.1039/d3ob00440f
日期:——
Reported herein is a transition-metal-free protocol for a regio- and diastereoselective synthesis of hydroxyalkyl group-embedded N-arylbenzo[b][1,4]oxazines and N-arylindolines based on an epoxide-opening cyclization/double Smiles rearrangement cascade of p-nosylamide-tethered epoxides. To the best of our knowledge, this is the first report of the integration of epoxide-opening cyclization with Smiles
Base-Mediated, Chemo- and Regioselective (4+2) Annulation of Indole-2-carboxamides with 2,3-Epoxy Tosylates toward 1,2-Fused Indoles
作者:Arup Jyoti Das、Sajal Kumar Das
DOI:10.1021/acs.joc.3c00813
日期:2023.7.7
indole-2-carboxamides with 2,3-epoxy tosylates has been explored. The protocol delivers 3-substituted pyrazino[1,2-a]indol-1-ones in high yields in diastereoselective fashion, and neither 4-substituted pyrazino[1,2-a]indol-1-ones nor tetrahydro-1H-[1,4]diazepino[1,2-a]indol-1-ones are generated, irrespective of whether the distal epoxide C3 substituent is alkyl or aryl, or the epoxide is cis- or trans-configured
已经探索了吲哚-2-甲酰胺与 2,3-环氧甲苯磺酸盐的碱介导[4+2]环化。该方案以非对映选择性方式以高产率提供 3-取代的吡嗪[1,2- a ]吲哚-1-酮,并且既不产生 4-取代的吡嗪[1,2- a ]吲哚-1-酮,也不产生四氢-1 H-无论远端环氧化物C3取代基是烷基还是芳基,或者环氧化物是顺式还是反式,都会生成[1,4]二氮杂[1,2- a ]吲哚-1-酮-配置。该反应通过用 2,3-环氧甲苯磺酸酯对吲哚支架进行 N-烷基化,同时进行 6-外选择性环氧化物开环反应,在一锅中进行。值得注意的是,该过程对于两种起始材料都具有化学和区域选择性。据我们所知,该过程代表了吲哚基二杂核亲核试剂与环氧化物基介电试剂一锅成环的第一个成功例子。