2- hetaryl

In cases where R = aryl, hetaryl, R = H (and others) a-keto-y-butyrolactones seem to exist entirely as enol tautomers [81JCS(P1)1969, 81TL1591 82G1 85CC340 86TL2015 92JOC4558],... 

Nitrosation of hetaryl acetic hydrazide 249 gives azide 250, which on thermolysis affords furazan 251 and 1,2,4-oxadiazole 252 (Scheme 165) (79JHC689). Depending on the solvent, different ratios of 251 and 252 were obtained. A higher proportion of furazan 251 (up to 70%) was formed in CHCI3. 

Transition metal-catalyzed synthesis of hetarylamines and hetaryl ethers from triflates and aryl/hetaryl halides or heterocyclic amines 98AG(E)2046. 

There are other examples of hydrogenation of l-(hetaryl)-4-alkynylpyrazole derivatives to the corresponding alkanes (96EUP703234). Derivatives of 5-ethynylpyrazolo[3,4-(i]pyrimidine in presence of 10% Pd/C were hydrogenated... 

Ethynylpyrazole was obtained under similar conditions in 46% yield (88M253). There are other examples of the trimethylsilyl cleavage with aqueous solution of potassium hydroxide for l-(hetaryl)-4-(trimethylsilylethynyl)pyrazole derivatives (96EUP703234). 

Bromo atom of ethyl (3S)-10-bromo-3-methyl-7-oxo-2,3-dihydro-7//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylate was change for hetaryl groups with tributylstannyl derivatives of heterocycles in the presence of (Ph3P)2Pd(II)Cl2 in boiling toluene (OOMIPIO). 7-Aryl-5-oxo-2,3-dihydro-5//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylates, 6-carboxamides and their 1,1-dioxide derivatives were prepared from 7-chloro derivatives in the... 

Of particular synthetic importance is the coupling of aryl- and hetarylboronic acids to aryl- and hetaryl halides (or triflates), allowing for a convenient synthesis of biphenyls, even sterically demanding derivatives such as 14, hetaryl phenyls and Zj/ -hetaryls. With appropriately disubstituted aromatic substrates, the Suzuki coupling reaction can be applied in the synthesis of polyphenylene materials. 

The Willgerodt reaction also works with hetaryl alkyl ketones, but often gives unsatisfactory yields. Yields generally decrease with increasing chain length of the alkyl group. 

In general, the triarylmethane leuco skeleton can be represented by structures 1-4. Traditional leuco di- and triphenylmethane dyes frequently include compounds of type 1 and 3. The closely related compounds 2 and 4 are derived from 1 and 3. Another closely related type is the lactone or phthalide 5 (see Chapter 4). In all of these leuco dyes, one or more of the phenyl rings can be replaced by a hetaryl ring or by a fused aromatic ring such as a naphthalene. 

In place of aromatic aldehyde, a hetaryl aldehyde such as 2-pyridinecar-boxaldehyde can also be used.84 If a hetaryl aldehyde such as 4-pyridinecar-boxaldehyde and a hetaryl nucleophile such as indole 61 are used, a trihetarylmethane of type 62 is formed91 (Eq. 8). The reaction normally occurs at the 3-position of indole. However, when the 3-position is substituted, the reaction occurs at the 2-position. Use of two different indoles... 

Methyl-4-oxo-47/-l,6,7,8,9,9a-hexahydro-47/-pyrido[l,2- ]pyrimidine-3-carboxylate has been N-alkylated <1997WO97/007116>. l-(Hetaryl) derivatives were prepared from l,2,3,4-tetrahydro-67/-pyrido[l,2-tf]pyrimidin-6-ones... 

The hetaryl displacement in 3,6-disubstituted 1,2,4,5-tetrazines with anhydro bases of N-methylquinaldiniums has been described <06MI99>. 

The instability of 5-aminoimidazoles (96) has led to in situ acylation being used to obtain stable compounds and using this approach several derivatives have been prepared. For example, a solution of the appropriate 5-nitroimidazole (97) in ethyl acetate was reduced with Raney nickel, and the resulting solution of 5-aminoimidazole (96) then treated with an acid chloride to give the amides (118 R1 = Me, R2 = S02Me, COPh, R3 = alkyl, aryl, hetaryl) (25-45%) [82IJC(B)1087],... 

A one-pot multistep process for the synthesis of 3-amino-4-aryl- and 3-amino-4-hetarylfurazans 271 from /Maryland 4-/3-hetaryl-/3-oxo acid esters 270 was developed (Scheme 70) <2005RCB1057>. 

Alkoxytrialkylstannanes react with alkynylcyclobutenones (101) to yield stannylated quinones285. The stannyl group can be displaced by aryl or hetaryl groups, as shown in reaction 32286a. 

Ohler, E., El-Badawi, M., and Zbiral, E., Synthese von Hetaryl- und Hetarylvi-nylphosphonsaureestern aus 2-Brom-l-oxoalkylphosphonaten und 4-Brom-3-oxo-l-alkenylphosphonaten, Chem. Ber., 117, 3034, 1984. 

Z- Configuration is typical of the majority of a-aryl(hetaryl)-/V-alkylaldo-nitrones. The isolation of -isomers in the condensation of aromatic aldehydes with iV-j3-]ihenyletli Tliydroxylamine has been described (155). The synthesis of a, N -diary lnitrones gives best results if acidic catalysis is employed (156), or when clay is used as a catalyst (157). Significant reduction of reaction time and increase in the yields of nitrones can be achieved if microwave irradiation is used (158, 159). On the basis of polymeric arylaldehydes, the synthesis of polymeric a,-diarylnitrones has been described (160). 

In most cases, the stereochemical course of heterocyclic addition can be altered by pre-complexation of nitrones with Lewis acids. In the absence of complexation agents (Et2AlCl, TiCLi), addition of lithio-hetaryl derivatives to chiral 3-alkoxy nitrones (292a-d) gives P-alkoxy-a-hydroxylamino-2-alkylhetaryls (346a-d) in good yields with. vy/i-selectivity. In the presence of diethylaluminum chloride the reaction leads to the same adducts, but with anti-selectivity (Scheme 2.150) (Table 2.12) (581). 

The 3-hetaryl-substituted 6-hydroxy- and 6-thiol[l,2,4]triazolo[3,4-A][l,2,4]thiadiazoles 28 and 29 on treatment with hydrazine hydrate gave the 3-hetaryl-substituted 4-amino-5-hydrazino-[l,2,4]triazoles 30 (Equation 3) <1990IJB135>. 

---