Helvetica Chimica Acta

Ishikura, Minoru; Takahashi, Norinobu; Yamada, Koji; Abe, Takumi; Yanada, Reiko

doi: 10.1002/hlca.200890195pmid: N/A

Palladium‐catalyzed tandem cyclization–cross‐coupling reaction of indolylborate 2 and vinyl bromide 5 was successfully applied in a short formal synthesis of olivacine. The reaction of 2 with 5 in the presence of Pd(OAc)2 readily afforded three kinds of products, triene derivative 6 and vinylindole derivative 7, along with a small amount of the piperidine derivative 8 (Scheme 2). On the other hand, the reactions of 2 with bromide 10 or 15 were also examined (Schemes 4 and 5), and their outcome markedly depended on the relative ease of ring closure as a function of ring size. Irradiation of 6 with a high‐pressure mercury lamp (→9; Scheme 2), followed by removal of the N‐[(benzyloxy)carbonyl] group and subsequent oxidation afforded, after deprotection, pyridocarbazole 23, and the conversion of 23 to olivacine is known (Scheme 6).

Collin, Marie‐Pierre; Hobbie, Sven N.; Böttger, Erik C.; Vasella, Andrea

doi: 10.1002/hlca.200890196pmid: N/A

In search for new antibiotics we replaced the amide moiety of lincomycin 1 by a 1,2,3‐triazole ring. The 1,2,3‐triazoles 10a–10k were obtained as single regioisomers by ‘click reaction’ of azide 5 with the alkyne 9k, derived from propyl hygric acid, and the alkyl, aryl, or cycloalkyl alkynes ribosomes 9a–9j. The new analogues proved inactive towards wild‐type and A2058G mutant.

Koneva, Ekaterina A.; Volcho, Konstantin P.; Gatilov, Yuri V.; Korchagina, Dina V.; Salnikov, Georgi E.; Salakhutdinov, Nariman F.

doi: 10.1002/hlca.200890197pmid: N/A

The reaction of (+)‐car‐2‐ene (4) with chlorosulfonyl isocyanate (=sulfuryl chloride isocyanate; ClSO2NCO) led to the tricyclic lactams 6 and 8 corresponding to the initial formation both of the tertiary carbenium and α‐cyclopropylcarbenium ions (Scheme 2). A number of optically active derivatives of β‐amino acids which are promising compounds for further use in asymmetric synthesis were synthesized from the lactams (see 16, 17, and 19–21 in Scheme 3).

Kikuchi, Masafumi; Yaoita, Yasunori; Kikuchi, Masao

doi: 10.1002/hlca.200890198pmid: N/A

Fourteen monohydroxy‐substituted polyunsaturated fatty acids, including two new compounds, (9Z,12S,13E,15Z)‐12‐hydroxyoctadeca‐9,13,15‐trienoic acid (10) and (9Z,12Z,14E,16R)‐16‐hydroxyoctadeca‐9,12,14‐trienoic acid (13), and 12 known ones, i.e., 1–9, 11, 12, and 14, were isolated from the whole plants of Swertia japonica Makino, and characterized as the corresponding methyl esters 1a–14a. Their structures were elucidated by analysis of the corresponding spectroscopic data, and the absolute configurations of 10a and 13a were determined by the Mosher‐ester method. The CD spectra (Table) of compounds 1a–14a are briefly discussed. This is the first report on the isolation of monohydroxy‐substituted polyunsaturated fatty acids from the Swertia genus in Gentianaceae.

Wu, Bin; Wu, Saiwei; Qu, Haibin; Cheng, Yiyu

doi: 10.1002/hlca.200890199pmid: N/A

Chemical investigation of the fruits of Viburnum dilatatum Thunb. resulted in the isolation and characterization of four new phenolic glycosides, jiamiziosides A–D (1–4), together with five known compounds. Their structures were established by spectroscopic means and by comparison with the literature values. The antioxidant activities of the new isolates were determined against 2,2‐diphenyl‐1‐picrylhydrazyl (=2,2‐diphenyl‐1‐(2,4,6‐trinitrophenyl)hydrazinyl; DPPH) and superoxide radicals. Among the compounds tested, jiamizioside C (3) possesses the most potent inhibitory scavenging effect on DPPH and superoxide radicals with IC50 values of 16.8 and 17.8 μM, respectively.

Yang, Guang‐Yu; Xiao, Wei‐Lie; Chang, Ying; Wang, Rui‐Rui; Pu, Jian‐Xin; Gao, Xue‐Mei; Lei, Chun; Lu, Yang; Zheng, Yong‐Tang; Sun, Han‐Dong

doi: 10.1002/hlca.200890200pmid: N/A

Three new highly oxygenated nortriterpenoids, wilsonianadilactones A–C (1–3), together with twelve known ones, i.e., 4–15, were isolated from the leaves and stems of Schisandra wilsoniana. Their structures were established by means of extensive analysis of spectroscopic data, and compound 1 was further confirmed by X‐ray crystallographic diffraction. Compounds 1–3 showed weak anti‐HIV‐1 activity with EC50 values of 23.5, 55.5, and 66.4 μg/ml, respectively.

Steinlin, Thomas; Sonati, Tiziana; Vasella, Andrea

doi: 10.1002/hlca.200890201pmid: N/A

Intramolecular condensation of the N‐(4‐amino‐5‐nitrosopyrimidin‐4‐yl)‐2‐chloroacetamide 2 led to the pteridinone N(5)‐oxide 4, while treatment of 2 with Me3P yielded the 8‐(chloromethyl)purine 3. A high‐yielding [3+2] dipolar cycloaddition of the N(5)‐oxide 4 to electron‐poor dipolarophiles, followed by spontaneous N,O‐bond cleavage, gave the C(6)‐substituted pteridinones 8a–8d that were deprotected to provide the pteridine‐4,7(3H,8H)‐diones 9a–9d, constituting a new synthesis of pterinones possessing a functionalised side chain at C(6).

Li, Dong‐Li; Li, Xiao‐Ming; Li, Tie‐Gang; Dang, Hong‐Yue; Wang, Bin‐Gui

doi: 10.1002/hlca.200890202pmid: N/A

Cultivation of the fungal strain Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus, resulted in the isolation of two new dioxopiperazine derivatives, namely, dehydrovariecolorin L (1) and dehydroechinulin (2), together with eight known dioxopiperazine compounds including variecolorin L (3), echinulin (4), isoechinulin A (5), dihydroxyisoechinulin A (6), preechinulin (7), neoechinulin A (8), neoechinulin E (9), and cryptoechinuline D (10). The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data as well as by comparison with literature. Compounds 1, 2, 9, and 10 were investigated for their α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) radical‐scavenging activity. In addition, the new compounds, 1 and 2, were evaluated for their cytotoxic activity against the P‐388, HL‐60, and A549 cell lines.