2-Ethoxy-3,4-dihydro-2H-pyran

The experimental procedure described is essentially one reported by Ziegler and Wilms 8 as subsequently modified,9 except that the glutaraldehyde is prepared from 2-ethoxy-3,4-dihydro-2H-pyran instead of cyclopentene ozonide 8 or pyridine via dihydropyridine and glutaraldehyde dioxime.9 Essentially these procedures have also been reported briefly by other investigators.10... 

Ethoxydihydropyran Z-2-Ethoxy-3,4-Dihydro-2H-Pyran Ethoxye thane 2-Ethoxyethanol 2-Ethoxyethanol, Acetate... 

SYNS 2-ETHOXY-2.3-DIHYDRO-Y-PYRAN 2-ETHOXY-3,4-DIHYDRO-l,2-PYR.- N 2-ETHOXY-3.4-DIHYDRO-2H-PYRAN... 

ETHOXY DIGLYCOL see CBROOO 2-ETHOXY DIHYDROPYRAN see EER500 2-ETHOXY-3,4-DIHYDRO-l,2-PYRAN see EER500 2-ETHOXY-3,4-DIHYDRO-2H-PYRAN see EER500 2-ETHOXY-2,3-DIHYDRO-y-PYRAN see EER500 6-ETHOXY-l,2-DIHYDRO-2,2,4-TRIMETHYLQUINOLINE see SAVOOO 1-ETHOXY-3,7-DIMETHYL-2,6-OCTADIENE see GDGIOO... 

Glutaraldehyde is conveniently prepared, by stirring a mixture of 120 g. of 2-ethoxy-3,4-dihydro-2H-pyrane, 300 ml. of water, and 25 ml. of coned, hydrochloric... 

ETHOXY-3,4-DIHYDRO-l,2-PYRAN or 2-ETHOXY-3,4-DIHYDRO-2h-PYRAN (103-75-3) Forms explosive mixture with air (flash point 108°F/42°C oc). Violent reaction with strong oxidizers. Incompatible with strong acids, nitrates. 

An ethanolic soln. of 2-ethoxy-3,4-dihydro-2H-pyran added dropwise during 2 hrs. to a gently refluxing mixture of water, coned. H2SO4, and 1 mole... 

Table 5.17 Hydroboration of 2-methoxy-3,4-dihydro-2H-pyran and 2-ethoxy-3,4-dihydro-2H-pyran [69]... 

Hydroboration of 2-methoxy-3,4-dihydro-2H-pyran and, 2-ethoxy-3,4-dihy-dro-2H-pyran have been studied, which afford the corresponding 5-hydroxy derivatives in excellent yields but with poor diastereoselectivity (Table 5.17) [69],... 

H-Pyran, 4-alkyl-5,6-dihydro-conformation, 3, 630 2H-Pyran, 5-alkyl-2-ethoxy-3,4-dihydro-reactions... 

A facile synthesis of cyclobutylmethanols has been devised by reacting 2-ethoxy-5-alkyl-3,4-dihydro-2H-pyrans with aluminum alkyls (Scheme 149) (80TL4525). When (648) is reacted with triisobutylaluminum the cyclobutylmethanol (649) is formed quantitatively. While several mechanisms have been proposed for this process, initial rupture of the carbon-oxygen bond of the pyran ring to form an aluminum enolate, which then undergoes ring closure and reduction, appears to be most likely. 

A cost effective and easily scaled-up process has been developed for the synthesis of (S)-3-[2- (methylsulfonyl)oxy ethoxy]-4-(triphenylmethoxy)-1 -butanol methanesulfonate, a key intermediate used in the synthesis of a protein kinase C inhibitor drug through a combination of hetero-Diels-Alder and biocatalytic reactions. The Diels-Alder reaction between ethyl glyoxylate and butadiene was used to make racemic 2-ethoxycarbonyl-3,6-dihydro-2H-pyran. Treatment of the racemic ester with Bacillus lentus protease resulted in the selective hydrolysis of the (R)-enantiomer and yielded (S)-2-ethoxycarbonyl-3,6-dihydro-2H-pyran in excellent optical purity, which was reduced to (S)-3,6-dihydro-2H-pyran-2-yl methanol. Tritylation of this alcohol, followed by reductive ozonolysis and mesylation afforded the product in 10-15% overall yield with excellent optical and chemical purity. Details of the process development work done on each step are given. 

Addition of bromine to 2-ethoxy-5,6-dihydro-2H-pyran (309) leads to two stereoisomeric 3,4-dibromo derivatives (310 and 311). Dehydrohalogenation of 310 and 311 with sodium ethoxide was found to afford four products, identified as trans-5,6-, trans-2,5-, ciJ-2,5-diethoxy-, and 3-bromo-2-ethoxy-5,6-dihydro-2H-pyrans (312-315), thus correcting an older study. ... 

Full experimental details have been published of the syntheses of kasugamycin (272, R = C(NH)C02H) from 3,4-dihydro-6-methyl-2H-pyran-2-one (271) and of methyl a-DL-mycaminoside (274), a-DL-oleandroside (275), a-DL-cy-maroside (276), a-DL-tyveloside (277), and a-DL-chromoside C(278) from 3,4-dihydro-2-ethoxy-6-methyl-2H-pyran (273). The schemes of these syntheses have been presented. ... 

Propinsaure 3-Ethoxy- -methylester E15/3, 3213 (H - Li - COOR) 2H-Pyran 4-Methoxy-2-oxo-5,6-dihydro- VI/2, 671 4H-Pyran 2-Carboxy-5,6-dihydro-VI/4, 87... 

However, when 36 was heated with a-amino heterocycles or with cyclic 1,3-dicarbonyl or potential 1,3-dicarbonyl compounds, 3-heteroarylp)rr-azol derivatives were obtained. In this manner 36 afforded, when heated with 2-aminopyridine and 3-amino-lH-pyrazol in acetic acid under reflux for 2 h and 5 h, respectively, 3-(5-ethoxy-l-phenyl-lH-pyrazol-3-yl)-4H-pyrido[l,2-fl]pyrimid-4-one (38) and 6-(5-ethoxy-l-phenyl-lH-p5rrazol-3-yl)pyrazolo[l,5-fl]pyrimid-7(lH)-one (39) in 70% and 77% 5deld, respectively. Similarly, 36 afforded with cyclicjS-dicarbonyl compounds, such as 4-hydroxy-6-methyl-2H-pyran-2-one and 5,5-dimethylcyclohexane-l,3-dione by heating in acetic acid for 4 h and 8 h, respectively, the corresponding 3-(5-ethoxy-l-phenyl-lH-pyrazol-3-yl)-7-methyl-2H,5H-pyrano[4,3- 7]pyran-2,5-dione (40) and 3-(5-ethoxy-l-phenyl-IH-pyrazol-3-yl)-7,7-dimethyl-7,8-dihydro-2H-chromene-2,5-dione (41) in 26% and 82% yield, respectively (Scheme 15). 

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