Three heteroatoms

Cross-coupling reactions on azoles with two and more heteroatoms  

Click chemistry (triazole synthesis and beyond) 07S1589. 

Copper-catalyzed azide-alkyne cycloaddition producing only 1,4-disub-stituted-1,2,3-triazoles at room temperature in excellent yields 07AA7. 

Cu -catalyzed alkyne-azide click cycloadditions, a mechanistic and synthetic perspective 06EJO51. 

N-Heterocyclic carbene-copper(I) complexes in homogeneous catalysis, particularly, of [3 + 2] cycloaddition of azides and alkynes 07SL2158. 

The unusually stable cross-ozonide 89 has been reported 06TA1780 , and a range of isomeric mono- and disulfoxides of the E-cyclooctene-derived 1,2,3-trithiolane 90 have been prepared 06T5441 . 

Zahouily, A. Mezdar, A. Elmakssoudi, B. Mounir, A. Rayadh, S. Sebti, H.B. Lazrek, Arkivoc 2006, ii, 31. 

Yamada, K. Fujimoto, H. Akutsu, S. Nakatsuji, A. Miyazaki, M. Aimatsu, S. Kudo, T. Enoki, K. Kikuchi, Chem. Commun. 2006, 1331. 

Ackermann, C.J. Gschrei, A. Althammer, M. Riederer, Chem. Commun. 2006, 1419. 

Takahashi, T. Watahiki, S. Kitazume, H. Yasuda, T. Sakakura, Chem. Commun. 2006, 1664. 

M N Cayen, R Gonzalez, E S Femandini E Gieselin, D R Hicks, M Kranii, and D Dvornik, Xenohiotica, 16, 251 (1986) 

10 M A OndettiandJ Krapcho, 1/ S Patent, 4,316,906 19S2) via Chem Abstr 96 218,225f (1982) 

In the 1,2,4-thiadiazole ring the electron density at the 5-position is markedly lower than at the 3-position, and this affects substituent reactions. 5-Halo derivatives, for example, approach the reactivity of 4-halopyrimidines. The 1,2,4-oxadiazole ring shows a similar difference between the 3-and 5-positions. 

Substituents in 1,3,4-thiadiazoles are quite strongly activated, as in the 2-position of pyridine. 

In contrast, substituents in 1,2,4-triazoles are usually rather similar in reactivity to those in benzene although nucleophilic substitution of halogen is somewhat easier, forcing conditions are required. 

Padmanilayam, B. Scorneaux, Y. Dong, J. Chollet, H. Matile, S.A. Charman, D.J. Creek, W.N. Charman, J.S. Tomas, C. Scheurer, S. Wittlin, R. Brun, J.L. Venerstrom, Bioorg. Med. Chem. Lett. 2006, 16, 5542. 

Chudinov, S.B. Gashev, V.V. Semenov, Russ. Chem. Bull. 2006, 55, 2238. 

Hansen, N. Thorup, I. Johannsen, K. Bechgaard, Acta Crystallogr., Sect. E 2007, 63, o2702. 

Sleep inducing dmgs go back to the very earliest days of medicinal chemistry. The earliest drugs comprise the barbiturates, which though effective had some 

The enzyme, purine nucleoside phosphorylase (PNP), is directly involved with blood levels of T-cells. Low levels of this enzyme will inhibit T-ceU prohferation. Drugs that inhibit the enzyme can also be expected to act against proliferation of malignant T-cells. The PNP inhibitor forodesine (36) has shown early activity against T-cell mahgnancies. Treatment of the deazapurine (32) with lithium leads to derivative 33 

Quinoline-containing 1,2,4-trioxolanes such as 107 have been patented as anti-malarial agents 05FRP2862304 . Further results on the reactivity of the novel 13,2-dioxathiolane-2-thione containing the cyclic thionosulfite function have appeared 05HCA1451 and a convenient method for direct conversion of 1,2-diols into cyclic sulfates using sulfuryl chloride has been described 05TA3908 . 

04HCA2296 C. Fu, A. Linden, H. Heimgartner, Helv. Chim. Acta 2004, 87, 2296. 

04MI443 I. Aoyagi, M. Katsuhara, T. Mori, Sci. Technol. Adv. Mater. 2004, 5, 443 [Chem. Abstr. 

04TL8211 R. Andreu, J. Garin, C. Lopez, J. Orduna, E. Levillain, Tetrahedron Lett. 2004, 45, 8211. 

05AG(E)7277 S. Nishida, Y. Morita, K. Fukui, K. Sato, D. Shiomi, T. Takai, K. Nakasuji, Angew. Chem. Int. Ed. 2005, 44, 7277. 

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Beyond the scope of this chapter, but similar in mode of formation and reactivity to the title compounds, are some three-membered rings with three heteroatoms. Oxadiaziridine... 

In using the tables, it would be best to survey the list of tables included in each chapter to determine how many categories might possibly contain the compound of interest. It should be noted that a large number of cyclophanes which contain fewer than three heteroatoms are not included in this book since they are not generally useful as cation binders. 

VI. Five Membered Heterocyclo-Quinolines with Three Heteroatoms. 162... 

Regarding the series of hetero aromatic pentacyclic compounds with three heteroatoms, an accelerated synthesis of 3,5-disubstituted 4-amino-1,2,4-triazoles 66 under microwave irradiation has been reported by thermic rearrangement of dihydro-1,2,4,5 tetrazine 65 (Scheme 22). This product was obtained by reaction of aromatic nitriles with hydrazine under microwave irradiation [53]. The main limitation of the method is that exclusively symmetrically 3,5-disubstituted (aromatic) triazoles can be obtained. 

Diazaphospholes constitute the most widely investigated class of heterophospholes, the 67t-aromatic phosphorus heterocycles [1,2]. Diazaphospholes are unique in the manner that the five-membered ring incorporates one phosphorus atom. First diazaphosphole representative, i.e. 2//-[l,2,3 diazaphospholc was obtained as early as 1967 [3] and until 1980s the interest of organophosphorus chemists remained in the development of different synthetic routes and in investigating their varied reactivity due to the structural diversity within the class [4], On the basis of the relative positions of the three heteroatoms in the five-membered ring, six monocyclic diazaphosphole systems (A-F) are possible and all of them have been reported (Structure 1). 

Synthesis from Heterocycles Containing Three Heteroatoms 336... 

There are very few reports concerning the use of heterocycles containing three heteroatoms for the synthesis of the target bicyclic systems. 

Table 2 Linearly fused (5 5 5) heterocycles with three heteroatoms...

Systems with more than three heteroatoms 828... 

Indolizines a- or b-Fused to a Five-Membered Ring Containing Two or Three Heteroatoms... 

Five-Membered Heterocycles with Three Heteroatoms 6.24.5.1 1,2,3-Triazoles... 

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