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201.
Two new rearranged spongian diterpenes designated omriolide A and B were isolated from the southern Kenyan sponge Dictyodendrilla aff. retiara collected at Wasini Is., Shimoni Channel. Omriolide A possesses an octalin linked to a unique trioxatricyclo[5.2.1.04,10]decane ring system, forming a tricyclic ‘cap’. Omriolide B comprised a tricyclo[5.4.0.02,4]undecane linked to a dioxabicyclo[3.3.0]octane. The structures of both diterpenes were elucidated by interpretation of MS results and, mainly, 1D and 2D NMR spectra. 相似文献
202.
CrystalStructureof3-[(α-Phenyl)triphenylgermylethyl]-4-phenyl-Δ~2-1,2,4-triazoline-5-thioneChenRu-Yu;LiFeng-Fu(InstituteofEle?.. 相似文献
203.
以苯基嘧啶/吡啶基嘧啶为母核, 同时引入2个三氟甲基(CF3)合成了2-[3,5-二(三氟甲基)苯基]-5-氟基嘧啶(tfmphfppm)和2-[2,6-二(三氟甲基)-4-吡啶基]-5-氟基嘧啶(tfmpyfppm)主配体, 并以2-(5-苯基-1,3,4-噁二唑-2-)苯酚(pop)为辅助配体合成了2种铱(III)配合物Ir(tfmphfppm)2(pop)和Ir(tfmpyfppm)2(pop), 其发射光谱峰分别位于484和504 nm, 分别属于蓝绿光和绿光发射, 发光量子效率分别达到76%和89%. 由于氮杂环和2,5-二苯基-1,3,4-噁二唑基团的存在, 配合物具有较低的最低未占据分子轨道(LUMO)能级和较高的电子迁移率. 以2种 铱(III)配合物为发光中心制备的有机电致发光器件(OLED)显示了较好的器件性能, 其最大亮度(Lmax)、 最大电流效率(ηc, max)、 最大功率效率(ηp, max)和最大外量子效率(EQEmax)分别为33379 cd/m2, 76.55 cd/A, 31.59 lm/W和26.7%; 并且该器件显示了比较小的效率滚降, 在亮度为1000 cd/m2时, 器件的ηc仍然可以达到72.71 cd/A. 本文结果表明, 氮杂环、 2,5-二苯基-1,3,4-噁二唑和三氟甲基基团可以有效提高铱(Ⅲ)配合物的发光性能和电子迁移率, 从而提高器件的性能. 相似文献
204.
Dr. Matthew P. Confer Taoguang Qu Prof. Dr. Paul A. Rupar Prof. Dr. David A. Dixon 《Chemphyschem》2022,23(9):e202200133
Strained ring systems play an important role in synthesis and can be characterized by the ring strain energy (RSE). The RSE of 3, 4, 5, and 6 membered saturated and unsaturated ring systems containing N, O, P, and S heteroatoms and H, F, SiMe3, and SO2Me substituents were calculated at the G3(MP2) composite correlated molecular orbital theory level using up to 5 models to predict the RSE. Generally, the RSE decreased as ring size increased with a substantial decrease from 4 to 5 membered rings. Replacement of a ring CH2 with P or S reduced the RSE, consistent with less angle strain. The RSE for unsaturated systems were generally greater than for saturated systems due to increased angle strain. No general trends were found with respect to substituent effects. The RSE values suggest that 3-pyrroline and 2-pyrroline and their derivatives may be able to support ring opening metathesis polymerization and warrant further study. 相似文献
205.
E. Vessally 《Journal of Structural Chemistry》2008,49(6):979-985
Energetic, geometric and magnetic criteria were applied to examine the stability and/or aromatic character for the cyclic molecules C 4 H 4 M (M = O, S, Se, Te, NH, PH, AsH and SbH) at B3LYP/6-311++G** and MP2/6-311++G** levels of theory. The isodesmic reactions and nuclear independent chemical shifts (NICS) calculations were utilized to examine the molecules for energetic and magnetic criteria, respectively. The isodesmic reaction energies reveal that thiophene (C 4 H 4 S, ?23.269 kcal/mol) and pyrrole (C 4 H 4 NH, ?20.804 kcal/mol) have the greatest aromatic stabilization energies and tellurophene (C 4 H 4 Te, ?15.114 kcal/mol) and stibole (C 4 H 4 SbH, ?1.169 kcal/mol) have the lowest aromatic stabilization energies in their corresponding groups at MP2/6-311++G**. The NICS calculations confirmed the results obtained through isodesmic reaction energies. 相似文献
206.
207.
Anil Malik Dr. Nand Kishor Gour Sakshi Bhatt Prof. Dr. Ramesh Chandra Deka Dr. Suman L. Jain 《European journal of organic chemistry》2023,26(11):e202201338
The synthesis of 2-oxazolidinones from a three component coupling reaction of amines, epoxides, and CO2. The reaction proceeds in the presence of 1,1,3,3-tetramethylguanidine under visible light irradiation at atmospheric pressure. The optimized structures of all species involved in the reaction mechanism along with transition states have been described based on the DFT calculations. The developed methodology represents a promising approach of employing CO2 as a naturally abundant and non-toxic carbon resource to produce profitable chemicals. 相似文献
208.
Dipak J. Dahatonde Aritra Ghosh Adilakshmi Vutla Dr. Sanjay Batra 《European journal of organic chemistry》2023,26(28):e202300355
Herein, we report the regioselective one-pot synthesis of 1,4,5-trisubstituted pyrazoles by reacting Morita-Baylis-Hillman (MBH) acetates derived from aryl aldehydes with alkyl or aryl hydrazines in the presence of iodine under aerobic conditions. The reaction proceeds through sequential SN2′ nucleophilic substitution of substituted hydrazine onto the MBH acetate, I2-catalyzed oxidation of the allylic hydrazine to allylic hydrazone, heating-induced intramolecular aza-Michael reaction and cyclization, and oxidative aromatization. The key intermediate, the s-trans allyl hydrazones were isolated in good yields by performing the reactions at room temperature. However, the allyl hydrazones prepared from the MBH acetates of aliphatic aldehydes did not furnish the pyrazole owing to the absence of an activated methylene group in the substrate. The synthetic applications of the pyrazoles in Ugi reactions, decarboxylative halogenation, Pd-catalyzed benzoylation of the N-aryl ring, and metal-free tetrazole synthesis has been demonstrated. 相似文献
209.
A series of novel tricyclic pyrimidine-fused 1,5-benzodiazepines (PFBZDs) was synthesized using an enaminone-based approach. The key step in the synthetic strategy involves the formation of the CCNMe2 structure on vicinal carbonyl groups of the 1H-1,5-benzodiazepine-2,4(3H,5H)-dione (BZD). The synthesis of pyrimidine-fused 1,5-benzodiazepines was performed by a simple and efficient method in good to excellent yields under mild and green conditions. The β-enaminoamide intermediates were condensed with thiourea and guanidine derivatives to form the corresponding tricyclic PFBZDs. But reaction of aminoguanidine, thiosemicarbazide, 4-phenylthiosemicarbazide and ethane-1,2-diamine with β-enaminoamides didn't produce any desired product and led to recovery of the corresponding starting BZD. 相似文献
210.
Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献