Acetaldehyde 2-bromo, acetals

A -(2 2-Diethoxyethyl)anilines are potential precursors of 2,3-unsubstituted indoles. A fair yield of 1-methylindole was obtained by cyclization of N-inethyl-M-(2,2-diethoxyethyl)aniline with BFj, but the procedure failed for indole itself[2], Nordlander and co-workers alkylated anilines with bromo-acetaldehyde diethyl acetal and then converted the products to N-trifliioro-acetyl derivatives[3]. These could be cyclized to l-(trifluoroacetyl)indoles in a mixture of trifluoroacetic acid and trifluoroacetic anhydride. Sundberg and... 

Acetaldehyde, bromo-, diethyl ACETAL, 23, 8 24, 3 Acetamide, 25, 36 /i-Acetaminobenzenesulfinate, SODIUM, 22, 31... 

The elimination of a molecule of halogen acid from halo acetals of acetaldehyde with powdered potassium hydroxide gives ketene acetals. However, the ti-bromo acetals of the homologs of acetaldehyde on similar treatment with potassium hydroxide or potassium 1-butoxide are converted into ctyjS-olefinic acetals. ... 

The diethyl acetals of acetaldehyde, propionaldehyde, isobutyraldehyde, and butyraldehyde are converted into at-bromo acetals when treated at 25-40° in sunlight or under irradiation by a 60 W lamp with A-bromosuccinimide added portionwise 651 the reaction being exothermic, cooling is required. This method gives purer products than do those described above, but the yields are no better. 

Acetaldehyde directed aldol addn. with, 56-57 —, 2-bromo-, acetals pr., 179 a2-synthon, 18... 

Phenyl-ethyl alcohol can be prepared by numerous methods, several of which are the subject-matter of patents. It may be prepared, for example, by the conversion of phenyl-bromo-lactic acid into phenyl-acetaldehyde, and then reducing this body with sodium. Or it may be prepared by reducing phenyl-acetic esters with sodium and absolute alcohol in the folio-wing manner —... 

The synthesis of benzo[6]thiophenes by the PPA-promoted cyclization of (arylthio)acetaldehyde dimethyl or diethyl acetals [Eq. (4)] was introduced by Tilak287, 288 in 1950 and improved in 1951.289 The acetals are readily prepared from aryl mercaptans and bromo-acetaldehyde dimethyl (or diethyl) acetal in the presence of sodium ethoxide, or by reaction of an aryllithium compound with [(MeO)2CHCH2S]2.290 Diethyl acetal as starting material sometimes gives better yields of product than the corresponding dimethyl acetal.291 Optimum yields of benzo[6]thiophenes are obtained when cyclization of the acetals is carried out under reduced pressure so that the lower boiling benzo[6]thiophenes distill as soon as they are formed. Experimental conditions for obtaining optimum yields vary from case... 

Abietic ACID, 32, 1 acid sodium salt of, 32, 4 diamylamine salt of, 32, 2 Acetaldehyde, 36, 60 Acetaldehyde, diphenyl-, 38, 26 Acetal formation, from pentaerythritol and benzaldehyde, 38, 65 Acetamide, 31, 17 Acetamide, N-bromo, 31,17 a-PHENYL-, 32, 92 Acetanilide, < -benzoyl-, 37, 2 Acetanilide, -benzoyl-2-methoxy-4-nitro, 37, 4... 

HYDROXYPROPYLATION Ethyl 3-bromo-propyl acetaldehyde acetal. 

The reduction of ethyl bromo[ " C]acetate can be stopped at the aldehyde level when the reaction is performed with DIBAL-H at low temperature. This has been demonstrated for doubly carbon-13-labeled material. The resulting bromo[ C2]acetaldehyde (1021 was not isolated but trapped with Ph3P to give the corresponding Wittig reagent 103. which was used for two sequential C2 extensions of the aldehyde 104 in the synthesis of... 

Hydrogen sulfide and aliphatic and aromatic thiols react readily with [ C]nitriles to give [ C]thioamides in yields of 45-70%. Upon treatment with a-halocarbonyl compounds they form [ C]thiazoles (Hantzsch thiazole synthesis). This was exploited for the synthesis of 2-(4-chlorophenyl)[2- C]thiazol-4-acetic acid f89. X = COOH) (Figure 7.23) and the 2-(2-phthalimidoethyl)-[2- C]tliiazole derivative 91 °. which were obtained when the corresponding thioamides M and 90 were treated with 1,3-dichloroacetone and bromo-acetaldehyde diethylacetal, respectively. As illustrated by the third example in Figure 7.23,... 

---