Synthesis and spectroscopic properties of some dideuterated cyanopyridines

4‐Cyanopyridine‐2,6‐d₂ ( 5a‐2,6‐d₂ ), 3‐cyanopyridine‐2,6‐d₂ ( 5b‐2,6‐d₂ ), and 2‐cyanopyridine‐4,6‐d₂ ( 5c‐4,6‐d₂ ) were synthesized from the corresponding 2‐, 3‐ or 4‐pyridinecarboxylic acid N‐oxides. These dideuterated products were characterized by their mass and NMR spectra.     

Stereoselective Synthesis of 4a-Methyloctahydrophenanthrenes: A Novel Approach. III. C-9 and C-10 Substituted Series

A general approach to substituted octahydrophenanthrenes was developed, which allows the stereoselective introduction of functionality at all positions. The procedure utilizes 4a-methyl-2,3,4,4a,9, 10-hexahydrophenanthrene 1, readily available from phenanthrene by reductive alkylation.     

Chemoselective functionalization of α-carbolines at the C-2, C-3, C-4, and C-6 positions using Suzuki-Miyaura reactions

The synthesis of 2-, 3-, 4-, and 6-substituted pyrido[2,3-b]indoles (α-carbolines) by palladium-catalyzed cross-coupling reactions from the corresponding halopyrido[2,3-b]indoles is described. A sequential and a one-pot chemoselective double Suzuki-Miyaura coupling route is presented for the synthesis of symmetrically and unsymmetrically disubstituted pyrido[2,3-b]indoles.     

Synthesis of linoleic acids combinatorially labeled at the vinylic positions as substrates for lipoxygenases

Mammalian lipoxygenases have been implicated in a number of inflammation-related human diseases. Soybean lipoxygenase-1 is the archetypical example of known lipoxygenases. Here we report the synthesis of linoleic acid and (11,11)-d2-linoleic acid which are combinatorially labeled at the vinylic positions (9, 10, 12, and 13). Combinatorial labeling schemes allow for the simultaneous determination of KIEs in enzymatic reactions using NMR. Substrates are, thus, available as probes of detailed mechanism in kinetic isotope effect (KIE) studies of lipoxygenases.     

Synthesis and Antitumor Activity of C-2／C-10 Modified Analogues of Docetaxel

Four 10-propionyl docetaxel analogues (lla-d) with 2α-amido substituents were prepared, and their antitumor activity against three solid tumor cell lines and their drug-resistant counterparts were determined.     

Stereochemische untersuchungen an C-10-disubstituierten C-9-hydroxyphäophorbiden der a-reihe

The diastereomeric 9-hydroxy pheophorbides 3a, b-1, 2 and 4a, b-1, 2 were prepared by reduction of the 10-alkoxy pheophorbides 1a, b and 2a, b with NaBH₄. Their absolute configuration at C-10 was determined by NMR- and ORD/CD-measurements as well as chemical correlation, the configuration at C-9 by IR- and mainly NMR-spectroscopy. For this purpose, the NMR-spectra of the 9-hydroxy pheophorbides 3a, b-1, 2 had completely to be assigned with the aid of the selectively deuterated alcohols 5a, b-1, 2. The configuration at C-10 is stable under the conditions of the alkaline reduction while C-9 partially epimerizes. The acidic alcoholysis of 3a, b-1, 2, however, proceeds by equilibration at C-10 and almost complete retention at C-9. The H-bonds between the 9-OH group and the C-10 substituents (-COOCH₃, -OCH₃ were investigated by NMR and IR spectroscopy.     

Total synthesis of Bengamide E and analogues by modification at C-2 and at terminal olefinic positions

[Reaction: see text]. The total synthesis of the natural product Bengamide E, one of the members of a new class of antitumor natural products of marine origin, is reported based on a convergent and flexible synthetic route featuring an oxirane ring-opening reaction and an olefin cross metathesis. In a similar way, analogues structurally modified at C-2 and at the terminal vinyl positions were prepared by introduction of various nucleophiles and alkyl substituents during the epoxide opening and the olefin cross metathesis steps, respectively. These studies demonstrate the validity of our synthetic strategy, although they reveal some problems associated with the olefin cross metathesis, whose efficiency depends on the substituent at the C-2 position as well as the steric environment of the alkene.     

Prostaglandin analogs modified at the 10 and 11 positions

A simplified methodology for the building of prostaglandins substituted at the 10 and 11 positions is presented.     

Synthesis of 10-nm scale oligothiophene molecular wires bearing anchor units at both terminal positions

Oligothiophenes with the length of ca.10 nm bearing anchor units (a protected thiol group or trimethylsilylethynyl) at both terminal positions in the conjugated backbone have been synthesized by the block-coupling synthetic strategy. Their electronic properties were clarified by spectroscopic and electrochemical measurements.     

C-10 substituted 19-norsteroids—VIII 10-cyanosteroids with an oxygen at C-3

A sythetic sequence leading to 3-keto-10-cyano steroids is described. A number of 10-cyano and 10β-cyano ring A ketols have been prepared, and their rearrangements observed. The effect of the 10-cyano group on the rearrangement and conformation of ring A ketols is discussed.     

Synthesis of the monocyclic nonaromatic C-1 to C-10 fragments of the milbemycins and avermectins.

The efficient synthesis of C-1 to C-10 monocyclic nonaromatic fragments of the milbemycins and avermectins has been achieved, in which the key step involved the stereoselective addition of 2-lithio-4-phenylthiobut-1-ene to a 3-hydroxycyclohexanone derivative.     

10,10-二吡啶甲基-9,10-二氢蒽的合成研究

蒽酮1和氯甲基吡啶盐酸盐2在甲苯中回流反应生成10,10-二吡啶甲基-9(10H)蒽酮(3),收率63％～68％;3用硼氢化钠还原生成10,10-二吡啶甲基-9,l0-二氢蒽-9-醇(4),收率87％～90％;蒽醇4在酸催化下发生歧化反应,得到还原产物10,10-二吡啶甲基-9,10-二氢蒽(5)和氧化产物蒽酮3.该歧化反应受催化剂、溶剂和反应温度等影响.当蒽醇4用三氟化硼为催化剂、甲苯为溶剂、回流反应,5的收率达到74％.所合成的新化合物都经1H NMR,13C NMR,MS和元素分析表征确认.     

Synthesis of 10-deazapteroic and 11-deazahomopteroic acids

The syntheses of 10-deazapteroic and 11-deazahomopteroic acids are described. These compounds along with their simple 6-phenylalkylpteridinol relatives were found to be inactive as antimalarial agents against the Plasmodium berghei or Plasmodium gallinaceum strains. 10-Deazapteroie acid was a potent growth inhibitor of Streptococcus faecium both in the pteridine and tetrahydropteridine forms.     

Twisted 9, 10-phenanthrenequinones: Chromatographic enrichment of enantiomers and barriers to racemization

The enantiomers (M) and (P) of helical 9, 10-phenanthrenequinones were enriched by liquid chromatography with enantiomeric purities of 0.31 to 0.95. Their barriers to racemization (Table 2) were compared with the ones of the corresponding hydrocarbons.