Other heterocycles

In this section we shall discuss papers involving solely or predominantly reactions of aryltins, noting where necessary the other types of organotin mentioned. [Pg.182]

Dimerization of 2-amino-3,4,6-tri-0-benzyl-2-deoxy-D-glucose with l.l -thionyl-or sulfonyl-di-imidazole gave the fructosazine and bis-tetrahydropyrano-piper-azine derivatives 73 and 74 in a ratio of 1 5, respectively a related compound appeared in Vol. 25, p.l32. The P-carboline derivative 75, isolated as a natural product from a hybrid plant cell culture product, was synthesized in six steps from tryptamine and ( )-4,5,6-tri-0-acetyl-2,3-dideoxy-D-ery/Aro-hex-2-enose. Thiazolo-triazoles such as 76, termed acyclo-C-nucleosides, were obtained on deacetylation of the product from condensation of peracetylated D-gluconic or galactaric acids with 4-araino-3-aryl-l,2,4-triazole-5-thiols in the presence of POCls. The related 1,2,4-triazole 77 and dihydroimidazole 78 were obtained by condensation of D-glucono-1,5-lactone with aminoguanidine and ethylenedia-mine, respectively, followed by acetylation then O-deacetylation. [Pg.153]

The fused 1,2,3-triazolino-pyrrolidine 84 was obtained by oxidation of 2,3,4-tri-0-acetyl-5-azido-5-deoxy-D-xylose dibenzyl dithioacetal with MCPBA, the reaction involving intramolecular dipolar cycloaddition of the azido group onto a 1,2-double bond formed by loss of acetic acid. A similar product was obtained from the D-rt o-analogue. Nucleotide analogues based on hexenopyranosyl phosphonic acid derivatives with a nucleoside base moiety linked at C-4 are covered in Chapters 9 (Section 2.6) and 17. [Pg.155]

Reagents i, BnONHa or BnNH2, HgCl2 ii, CF3CO2H iii, Resin (OhT) iv. H2NCH2 NHC0(CH2)3C02H v. LiOH, MeOH [Pg.156]

3-Deoxy-3-imidazolyl-substituted cyclodextrins are covered in Chapter 4, and bis-(glucos-3-yl)-bipyridine in Chapter 14. [Pg.156]

Huyghes-Despointes and V.A. Yaylayan, J. Agric. Food Chem., 1996, 44, 1464 Chem. Abstr., 1996,125,11 277). [Pg.156]

The fused oxazole derivative 100 was synthesized from 3-azido-3-deoxy-l,2 5,6-di-O-isopropylidene-a-D-allofuranose, the key final step being the reaction of methyl 3-amino-3-deoxy-5,6-0-isopropylidene-p-D-alloside with DMF dimethyl acetal. The annelated pyranoside 101 was obtained by cyclization of a branched chain hexosulose derivative, and the fused triazole-piperidinoses such as 102 were made by a radical cyclization of a 3-pyrazolo-6-iodo-sugar derivative. The spiro-isoxazohne 103 and related isomers have been synthesized by dipolar cycloadditions of mesitonitrile oxide to 2-deoxy-2-C-methyl-ene-pentonic acids, themselves available in five steps from D-mannitol. Intra- [Pg.150]

Condensation of D-glucose with 1,2-diaminobenzene or its 3-substituted-de-rivatives, then with hydrazine, provided the pyrazoloquinoxalines 107/ Triazolopyrimidopurines such as 108 (and a regioisomer) were obtained by cycloaddition of an acetylene-substituted heterocycle with a 1-azido-l-deoxy-alditol derivatives/ [Pg.151]

The thiazoline derivative 109 was obtained as a single isomer by condensation of the corresponding 1,6-D-galactodialdehyde diacetal with 2-chloro-2-methyl-propanal, ammonia and sodium sulfide/ The multi-step synthesis of 3-trialkyl-silypyrazole derivatives such as 110 from 5,6-dihydroxy-sugar derivatives has been described/ [Pg.151]

117 and 118, lacked a heteroatom bonded exo to The 2-acetamido-2-deoxy-D-glucose mimics 119 and 120 were potent inhibitors of bovine kidney N-acetylglucosaminidase Ki values of 4 and 34 nM, respectively). The isoquinuclidine derivative 121, synthesized from 3-hydroxy-2-pyridone, mimics a mannopyranoside boat conformation and was an inhibitor of snail p-man-nosidase Ki = 20 The synthesis of N iV -bridged 6-amino-1,6- [Pg.153]

Schwogler, V. Gramlich and T. Carell, Helv. Chim. Acta, 2000,83,2452. [Pg.153]

Compared to other heterocyclic thiones (S3, SS, 56), A-4-thiazoiine-2-thione (54) is among the most reactive (43, 117). The observed order of reactivity is kgg > kn... [Pg.391]

A 2-methylthio substituent decreases the basicity of thiazole pK = 2.52) by 0.6 pK unit (269). The usual bathochromic shift associated with this substituent in other heterocycles is also found for the thiazole ring (41 nm) (56). The ring protons of thiazole are shielded by this substituent the NMR spectrum of 2-methylthiothiazole is (internal TMS, solvent acetone) 3.32 (S-Me) 7.3 (C -H) 6.95 (Cj-H) (56, 270). Typical NMR spectra of 2-thioalkylthiazoles are given in Ref. 266. [Pg.404]

Mercaptoselenazoies with Q to C,o cyclic hydrocarbon substituents in the 4-position have been mentioned as giving negative images from photosolubie emulsions (38. 39). Equally cited are other heterocycles such as thiazole. oxazole, or imidazole. [Pg.237]

IV, Other Heterocycles Directly Derived from Selenaaole... [Pg.259]

For solvolysis carried out at 25°C, the correlation gives the following values for p -6.15 for series 262 and -6.68 for series 263. The p values obtained for five other heterocycles and for benzene appear to be related... [Pg.148]

VIII. THIAZOLES FROM OTHER HETEROCYCLIC COMPOUNDS... [Pg.308]

Closing this chapter on thiazoie synthetic methods, I would like to point out that it is possible to obtain thiazoles from other heterocyclic compounds. [Pg.308]

VIII. Thiazoles from Other Heterocyclic Compounds... [Pg.309]

Other Heterocyclic Systems. Naphthalimides (15), where R = —NHCOR, are derivatives of 4-anTinonaphthalimide (69) and are used in plastics. The alkoxynaphthalimides (15, R = OCH ) (70,71) are of particular interest as fluorescent whitening agents. [Pg.118]

Other Heterocyclic Nitrogen Derivative Herbicides. The herbicides in this group are heterocycHc nitrogen derivatives that do not readily fall into one of the previously discussed groups. They have a wide range of uses and properties. Most of these herbicides are used for selective, pre-and/or post-emergence weed control. Amitrole is used for post-emergence, nonselective weed control in non-croplands and also as an aquatic herbicide (2,296). [Pg.53]

All lation of A Heterocycles. Indoles (25), imida2oles (26), pyra2oles (27), ben2otria2oles (27), or other heterocycles are generally alkylated in the presence of 50% aqueous NaOH and catalyst hen 2y1triethy1 amm onium chloride without solvent or in chloroben2ene or toluene. [Pg.189]

Other Heterocyclic Compounds. l,3-DichlorotetrahydroquiQa2oliQe-2,4-dione [23767-45-5] is useful as a laundry bleach. 2-Chloro-4-thia2olines are useful reagents for organic synthesis (167). N-Chloropiperidines, A/-chloropiperidones, and... [Pg.458]

There are several examples of the formation of pyridazines from other heterocycles, such as azirines, furans, pyrroles, isoxazoles, pyrazoles or pyrans and by ring contraction of 1,2-diazepines. Their formation is mentioned in Section 2.12.6.3.2. [Pg.52]

Syntheses of the Pyrimidine Ring from Other Heterocycles... [Pg.57]

Despite considerable localization of tt-electrons at the nitrogen atoms of pyrimidine, the ring system is still sufficiently aromatic to possess substantial stability. This is a great advantage in the primary synthesis of pyrimidines, in the synthesis of pyrimidines from the breakdown or modification of other heterocyclic systems and in the myriad of metatheses required to synthesize specifically substituted pyrimidines. [Pg.106]

Use of Caro s acid does result in di-AT-oxidation of 2,3-dichloropyrazine and 2,3-dichloroquinoxaline, but it is of interest to note that other heterocycles such as pyridine... [Pg.169]

Transformations from Other Heterocyclic Ring Systems... [Pg.263]

The He(Ia) photoelectron spectra of the parent heterocycles have been the subject of much study. Initially the assignment of the ionization energies to appropriate occupied molecular orbitals was confused by the unexpected reversal in the sequence of the two highest occupied MOs in tellurophene relative to the other heterocycles. The reported values are compared in Table 24. The assignments are based upon comparisons with the spectra... [Pg.24]

The course of the acid catalyzed dehydration of 1,4-diketones to furans, known as the Paal-Knorr method (1884CB2756), entails the formal addition of the enol of one carbonyl group to the other carbonyl. Examples which illustrate some of the routes used to make the necessary 1,4-diketones are shown in Scheme 13. Few examples are known of the preparation of the other heterocycles by this general approach using isolated intermediates, although some of the ring closures discussed in Section 3.03.3.1.1 are mechanistically equivalent. One example of the preparation of a hydroxypyrrole is included in Scheme 13 <59AC(R)2075). [Pg.97]

Photochemical fragmentation Equilibria with open-chain compounds Rearrangement to other heterocyclic species Polymerization... [Pg.39]

In theory, three isoxazolines are capable of existence 2-isoxazoline (2), 3-isoxazoline and 4-isoxazoline. The position of the double bond may also be designated by the use of the prefix A with an appropriate numerical superscript. Of these only the 2-isoxazolines have been investigated in any detail. The preparation of the first isoxazoline, 3,5-diphenyl-2-isoxazoline, from the reaction of )3-chloro-)3-phenylpropiophenone with hydroxylamine was reported in 1895 (1895CB957). Two major syntheses of 2-isoxazolines are the cycloaddition of nitrile A-oxides to alkenes and the reaction of a,/3-unsaturated ketones with hydroxylamine. Since 2-isoxazolines are readily oxidized to isoxazoles and possess some of the unique properties of isoxazoles, they also serve as key intermediates for the synthesis of other heterocycles and natural products. [Pg.3]

The preparation of isoxazolidine derivatives was first reported by Bodforss in 1918 (18CB192). The major synthesis of isoxazolidines involves the cycloaddition of nitrones with alkenes, and isoxazolidines have also enjoyed an increasing use as key intermediates in the synthesis of natural products and other heterocycles (79ACR396, 1892CB1498, 1892CB3291, 1882CB2105). [Pg.3]

Benzisoxazoles undergo electrophilic substitution in the benzo ring, but with nucleophiles the reaction occurs in the isoxazole moiety, often leading to salicylonitriles with 3-unsubstituted systems. The isomeric 2,1-benzisoxazoles are characterized by the ease with which they may be converted into other heterocyclic systems. [Pg.12]

A number of manipulations on isoxazolinone can be performed with the nucleus remaining intact, and a variety of reagents cleave the ring. Isoxazolin-5-ones have also been used as synthons for the production of other heterocycles (76ZC270). [Pg.39]

Other heterocycles which provide the CCC component in related ring transformations are benzodiazepine-3-carbonitrile (80CPB567), benzotriazepines (74T2765), azaxanthones (75JOC1734), acyloxiranes (61AP769) and oxetanones (65CPB248). [Pg.80]

Other heterocycles which rearrange to isoxazoles are pyridazine 1,2-dioxides (77CC856) and pyridinium salts (80CPB2083), although these transformations are of little synthetic importance. [Pg.82]

SYNTHESIS FROM OTHER HETEROCYCLIC COMPOUNDS 4.17.10.1 From Six-membered Heterocycles... [Pg.170]

Formation from other heterocyclic systems 5.05.6.4 Conclusions... [Pg.96]

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