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Polyallenes prepared with the aid of organoaluminum-VOCl3 catalysts appear to exist in three distinct phases: two crystalline phases (I and II) and an amorphous phase. Phase I shows two strong X-ray diffraction peaks at d = 5.62 Å and d = 4.04 Å; phase II has three strong peaks at d = 6.28 Å, d = 5.03 Å, and d = 4.21 Å. The band of the amorphous phase has its maximum at about d = 5.6 Å. 相似文献
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Bioguided Isolation and Antiproliferative Activity of Constituents from Smilax korthalsii A.D.C. Leaves
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Abdulmumeen A. Hamid Olapeju O. Aiyelaagbe Arvind S. Negi Suaib Luqman Fatima Kaneez 《中国化学会会志》2016,63(7):562-571
Ethyl acetate extract of Smilax korthalsii A.D.C. leaves exhibited antiproliferative activity on leukaemia carcinoma K562, hepatic liver cancer cells WRL and colorectal carcinoma with IC50 of 125.20, 46.10 and 160.00 μM respectively. Isolation of the bioactive ethyl acetate extract of Smilax korthalsii A.D.C. leaves gave eight compounds; 3β‐hydroxyspirost‐5‐ene (diosgenin), 1 , β‐sitosterol, 2 , lup‐5,11,20‐trien‐23‐ol, 3 , uneicos‐9‐enoic acid, 4 , ethylheptadecan‐17‐oic‐9‐enoate, 5 , cis‐octadec‐9‐enoic acid, 6 , hexadec9‐enoic acid, 7 and 11‐methyltridec‐12‐en‐1‐ol, 8 . The isolated compounds were tested against four human cancer cell lines: leukaemia carcinoma, K‐562; hepatic liver cancer cells, WRL; colorectal carcinoma, COLO; and breast carcinoma, MCF‐7 using the MTT assay. Diosgenin 1 exhibited significant antiproliferative activity against all four cell lines (IC50; K562=6.25, WRL=14.34, COLO=38.00, MCF‐7=12.40 μM), while compounds 3, 6 and 7 inhibited the growth of K‐562 at 20, 50 and 100 μM concentrations with IC50 of 90.20, 75.92 and 50.72 μM respectively. Other isolated compounds also showed cytotoxic properties against K‐562, WRL and COLO, but showed low inhibition of MCF‐7. 相似文献
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Our approach to achieve a partial synthesis of methanopterin ( 1 ) started from 6‐acetyl‐O4‐isopropyl‐7‐methylpterin ( 20 ) which was obtained either by condensation from 6‐isopropoxypyrimidine‐2,4,5‐triamine ( 19 ) and pentane‐2,3,4‐trione ( 6 ) or from 6‐isopropoxy‐5‐nitrosopyrimidine‐2,4‐diamine ( 21 ) and pentane‐2,4‐dione (=acetylacetone; 22 ) (Scheme 2). NaBH4 reduction of 20 led to 6‐(1‐hydroxyethyl)‐O4‐isopropyl‐7‐methylpterin ( 23 ) which was converted into the corresponding 6‐(1‐chloroethyl) and 6‐(1‐bromoethyl) derivatives 24 and 25 . A series of nucleophilic displacement reactions in the side chain and at position 4 were performed as model reactions to give 26 – 29, 32 – 35 , and 39 – 41 . Hydrolysis of the substituents at C(4) led to the corresponding pterin derivatives 30, 31, 36 – 38 , and 42 . Analogously, 25 reacted with 1‐(4‐aminophenyl)‐1‐deoxy‐2,3: 4,5‐di‐O‐isopropylidene‐D ‐ribitol ( 43 ), prepared from N‐(4‐bromophenyl)benzamide ( 47 ) via 49 and 50 to give 1‐{4‐{{1‐[2‐amino‐7‐methyl‐4‐(1‐methylethoxy)pteridin‐6‐yl]ethyl}amino}phenyl}‐1‐deoxy‐D ‐ribitol ( 44 ) in 62% yield (Scheme 3). Acid cleavage of the isopropylidene groups at room temperature led to 45 and on boiling to 1‐{4‐{[1‐(2‐amino‐3,4‐dihydro‐7‐methyl‐4‐oxopteridin‐6‐yl)ethyl]amino}phenyl}‐1‐deoxy‐D ‐ribitol ( 46 ). The next step, however, attachment of the ribofuranosyl moiety with 55 or 56 to the terminal 1‐deoxy‐D ‐ribitol OH group could not been achieved. The second component, bis(4‐nitrobenzyl) 2‐{[(2‐cyanoethoxy)(diisopropylamino)phosphino]oxy}pentanedioate ( 61 ), to built‐up methanopterin ( 1 ) was synthesized from 2‐hydroxypentanedioic acid ( 59 ) and worked well in another model reaction on phosphitylation with N6‐benzoyl‐2′,3′‐O‐isopropylideneadenosine and oxidation to give 62 (Scheme 6). 相似文献
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Wolfgang Pfleiderer 《Helvetica chimica acta》2008,91(2):338-353
A variety of pyrimidine precursors 12 – 25 were converted into a series of new 7‐hydroxylumazines (=7‐hydroxypteridine‐2,4(1H,3H)‐diones) 26 – 35 which functioned as starting materials for the transformation into the corresponding 7‐chlorolumazines 36 – 45 . Subsequent reaction with hydrazine led to the 7‐hydrazinolumazines 46 – 55 which gave on nitrosation the 7‐azidolumazines 1 and 56 – 64 . These compounds were subjected to short heating in xylene whereby 1 and 56 – 61 showed a new pteridine–purine interconversion in forming a new type of 1,3‐disubstituted or 3‐substituted xanthin‐8‐amine‐derived nitrilium ylides (2,3,6,7‐tetrahydro‐N‐methylidyne‐2,6‐dioxo‐1H‐purin‐8‐aminium ylides) 11 and 65 – 70 . The presence of an additional 6‐alkyl substituent in the 7‐azidolumazines 63 and 64 or of an unsubstituted N(3) position in 62 caused further rearrangement to xanthine‐9‐carbonitriles 71 – 73 . Prolonged heating of 7‐azido‐1,3‐dimethyllumazine ( 1 ) also afforded theophylline‐9‐carbonitrile (=1,2,3,6‐tetrahydro‐1,3‐dimethyl‐2,6‐dioxo‐9H‐purine‐9‐carbonitrile; 5 ). The nitrilium ylide function was established by NMR and UV spectra as well as by elemental analyses. Confirmation of the nitrilium ylide structures was suggested by the result of the heating of 1,3‐dimethyl‐N‐methylidynexanthin‐8‐aminium ylide 11 in EtOH or of 1 in pentan‐1‐ol leading to 8‐aminotheophylline (=8‐amino‐3,7‐dihydro‐1,3‐dimethyl‐1H‐purin‐2,6‐dione; 74 ). 相似文献
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Anew and 20 known compounds were isolated from Bidens pilosa L. var. minor (Blume) Sherff. The new compound was determined as 7‐phenyl‐hepta‐4,6‐diyne‐2‐ol by various physical techniques (MS, IR, UV, 1H‐, 13C‐NMR, and 2D‐NMR). 相似文献
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Bin Wang Wei‐Dong Zhang Yun‐Heng Shen Jian Tang Chuan Zhang Run‐hui Liu Min Lin Hui‐Liang Li 《Helvetica chimica acta》2008,91(2):244-248
Phytochemical studies on Veratrum nigrum L., collected in Shanxi, P. R. China, resulted in the isolation of two new steroidal alkaloids, 23‐methoxycyclopamine ( 1 ) and 15‐O‐(2‐methylbutanoyl)‐3‐O‐veratroylprotoverine ( 2 ). The structures of the two new compounds were established by means of extensive NMR spectroscopic studies. 相似文献
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