Ethyl orthoformate, condensation with

Ethyl-2-methyi-4-phenylthiazolium salts, on hydrobase of, 39 3-Ethyi-5-methyl-2-(p-dimethylamino-styiyl) thiazolium iodide, 29 Ethyl orthoformate, condensation with, thiazolium salts, 49 in synthesis of. chain-bridged thiazolocyanines, 58 thiazolocyanines. 58... 

On the other hand, 1,1,1-trisubstituted alkanes behave similarly to aldehydes, yielding pyrjdium salts (128) with identical substituents in positions 2 and 6. Thus, Dorofeenko and co-workers condensed 2 moles of acetophenone with 1 mole of benzotrichloride in the presence of perchloric acid obtaining 2,4,6-triphenjdpjTylium perchlorate with 1 mole of ethyl orthoformate, they obtained 2,6-diphenyl-pyrylium perchlorate (57) from o-hydroxyacetophenone, ortho-formic ester and perchloric acid, 4-ethoxybenzopyrylium perchlorate was formed. 

The methiodide and ethiodide of 4-methylcinnoline possess methyl groups which condense easily with aldehydes, and even with ethyl orthoformate,to give polymethine derivatives. These reactions, particularly that with the ortho ester, suggest that the salts have structure 55 (R = Me or Et, R = Me). The methiodide of 3-methylcinnoline also reacts with aldehydes, although more slowly, but no reaction with ethyl orthoformate has been reported. Although 55 (R = Me) appears to be the most likely structure for the product, the 4-methyl group may direct the quatemization on and,... 

Reaction of 2,4-xylidine with methylamine and ethyl orthoformate leads to the amidine 119 condensation of that product with a second mole each of orthoformate and 2,4-xylidine gives the scabicide amitraz (120) [29]. 

Furthermore, the homologous complex 286 condenses with ethyl orthoformate to give, in the course of a new y-tropolone synthesis, tropolone ether 287 by O-ethylation it is transformed to tropylium salt 288 (Scheme 72 70JA6382) the corresponding tropone complex was synthesized from dibenzotroporic and Cr (CO)6 [83AG(S)734]. 

Condensation of 2-mol equivalents of 9-aminocarbazole with ethyl orthoformate-boron trifluoride yielded the formamidine 127, which was oxidized with lead dioxide to the spectrally observable radical 128 in solution. ... 

Closely related are the cyanine dyes, for example cyanine (62) itself, which is formed from the ethiodide salts of lepidine and 4-iodoquinoline in the presence of base (Scheme 51). Analogous monomethine cyanines can have the quinoline nuclei linked 2,2 (pseudocyanines) and 2,4 (isocyanines). Quinaldine ethiodide on condensation With ethyl orthoformate gives the 2,2 -linked trimethine cyanine (carbocyanine) (63), known as pinacyanol (Scheme 51). 

The Bayer synthesis of ciprofloxacin (1) patented in 1981 utilized 2,4-dichloro-5-fluorobenzoyl chloride (15) as the starting material. With the aide of magnesium ethoxide, condensation of acid chloride 15 and diethyl malonate assembled ketone 16, which was subsequently decarboxylated using tosylic acid to form ethyl 2,4-dichloro-5-fluorobenzoylacetate (17) in 82% yield in two steps from 15. A Dieckman-like condensation of 17 with ethyl orthoformate was carried out in refluxing acetic anhydride... 

Condensation, of paraldehyde with diethyl malonate, 32, 54 of a-phene thyl chloride with diphenylacetonitrile, 39, 74 of phenylacetylene with ethyl orthoformate, 39, 59 of 1-phenylbiguanide with ethyl chloroacetate, 38,1 of potassium diphenylacetonitrile with benzyl chloride, 39, 73 of potassium trithiocarbonate with potassium chloroacetate, 39, 77 of sodium acetylacetonate to tetraacetylethane, 39, 61 of sodium formylacetone with cyano-acetamide, 32, 32 of tetracyanoethylene with N,N-dimethylaniline, 39, 68 of thiophene, paraldehyde, and hydrogen chloride, 38, 86 of thiourea with furfuryl alcohol, 36,66... 

Aminopyridazine-3-carboxamide condenses with urea and ethyl orthoformate to give pyrimido[5,4-c]pyridazine-6,8-dione and pyrimido[5,4-c]pyridazin-8-one, respectively. In like manner, 8-aminopyrimido[5,4-c]pyridazine is formed by the reaction of 4-amino-3-cyanopyridazine with formamide (68JHC523). 

Decitabine (1) was first synthesized in 1964 by a multistep procedure described by Pliml and Sorm.17 In this preliminary communication, 5-aza-2 -deoxycytidine was prepared via cyclization of the peracylglycosyl isocyanate 5, which was prepared from silver cyanate and chloride 4.18,19 Addition of 2-methylisourea to 5 afforded the crystalline intermediate 6. Condensation of isobiuret derivative 6 with ethyl orthoformate resulted in the formation of crystalline triazine 7. Prolonged treatment with methanolic ammonia at room temperature afforded 1 -(2-deoxy-D-ribofiiranosyl)-5-azacytosine (8) as a mixture of a and (3 anomers. No yield was reported as the authors did not separate or distinguish between decitabine (1) and its a-anomer. 

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