Bromoacetaldehyde diethyl acetal

Laurino examined a similar method in which methanesulfonanilides were alkylated with bromoacetaldehyde diethyl acetal and then cyclized with TiCU[4J. 1 hese methods presumably involve generation of an electrophilic intermediate from the acetal functionality, followed by an intramolecular Friedel-Crafts reaction. As a consequence, the cyclization is favoured by ER substituents and retarded by EW groups on the benzene ring. 

Disubstituted furans are available from the combination of P-dicarbonyl compounds with bromoacetaldehyde diethyl acetal (44). For example, dibenzoylmethane (45) reacts with acetal 44 to furnish 2,3-disubstituted furan 46 in 77% yield. This two-... 

Treatment of 2- 5//-dibenz[i>,/]azepin-5-yl acetaldehyde (16), prepared in 68% yield by /V-alkylation of 5/7-dibenz[A,/]azepine with bromoacetaldehyde diethyl acetal followed by acid hydrolysis, with methyl hydroxylamine yields the isolable nitrone 17, which in refluxing toluene undergoes intramolecular 1,3-dipolar cycloaddition at the CIO —Cl 1 alkene bond to give 2,3,3a, 12b-tetrahydro-2-methyl-3,8-methano-8//-dibenz[i>,/]isoxazolo[4,5-r/]azepine (18).235... 

The acetal 1, obtained from salicylamide and bromoacetaldehyde diethyl acetal, cyclizes on heating to provide l,4-benzoxazepin-5(4//)-one (2).32... 

Similarly, the monothione 24 reacts with acetylhydrazine to give the [l,2,4]triazolo[4,3-a][l,5]benzodiazepinone 25 with prop-2-ynamine the imidazo[1,2- ][1,5]benzodiazepinone 26 is produced and bromoacetaldehyde diethyl acetal provides the thiazolo[3,2-a][l, 5]ben-zodiazepinonc 27.282... 

BrN3 13973-87-0) see Cefoxitin bromoacetaldehyde diethyl acetal (C6H 3Bt02 2032-35-1) see Domiodol bromoacetaldehyde ethylene acetal (C4H7Br02 4360-63-8) see Carbimazole IV-bromoacetamide... 

Two sequential lithiations and treatments with different bifunctional electrophiles make possible one-pot syntheses of relatively complex molecules. Thus, in the [1+2+2] annulation depicted in Scheme 69, alkylation of 1-benzylbenzotriazole 399 with 2-bromoacetaldehyde diethyl acetal to give intermediate 426 is followed by alkylation with W-benzylideneaniline to produce derivative 427. Following treatment with formic acid causes cyclization to ethoxypyrrolidine 428 that subsequently eliminates ethanol and benzotriazole to give pyrrole 429 <1997JHC1379>. 

Bromoacetaldehyde diethyl acetal, b317 Bromoanisoles, b357, b358, b359... 

The literature is replete with synthetic methods to prepare 5-bromofurans. One of the more practical syntheses [10, 11] commenced with etherification of 4-bromophenol with bromoacetaldehyde diethyl acetal using either NaH in DMF or KOH in DMSO. Treatment of the resulting aryloxyacetaldehyde acetal with polyphosphoric acid (PPA) afforded 5-bromofuran in good yield via intramolecular cyclocondensation. However, cyclization of m-aryloxyacetaldehyde acetal 1 resulted in a mixture of two regioisomers, 6-bromofuran (2) and 4-bromofiiran (3). Finally, 7-bromofuran 5 can be prepared similarly using the intramolecular cyclocondensation of aryloxyacetaldehyde acetal 4 generated from etherification of 2-bromophenol with bromoacetaldehyde diethyl acetal. 

Fuostifoline (47), a furo[3,2-a]carbazole, was isolated from Murraya euchrestifolia. Timdri s total synthesis of 47 commenced with alkylation of bromocresol 43 with bromoacetaldehyde diethyl acetal and P4Oio-promoted cyclization to furnish 5-bromo-7-methylbenzofuran (44) [47]. The Suzuki coupling of boronic acid 45, derived from 44, with o-bromonitrobenzene yielded biaryl 46. Nitrene generation, achieved via deoxygenation of nitro compound 46 using triethyl phosphite, was followed by cyclization to fuostifoline (47). 

A reported procedure based on lithium diisopropylamide induced double elimination of ethanol from bromoacetaldehyde diethyl acetal also was not very effective for the large scale preparation of phenylthioacetylene.8 Another more recent synthesis of the title compound relies on the reaction of dimethyl(chloroethynyl)carbinol with an alkali metal phenylthiolate, followed by... 

Bromination of o-cresol (1133) led to 5-bromocresol (1134), which, on alkylation with bromoacetaldehyde diethyl acetal, followed by P20s-promoted cyclization in... 

A. Diethyl 2,2-Diethoxyethylphosphonate (Note 1). Into a 2-1., three-necked round-bottomed flask fitted with a magnetic stirrer, dropping funnel, and nitrogen inlet is placed 410 g. (2.08 moles) of bromoacetaldehyde diethyl acetal (Note 2), and a gentle stream of nitrogen is then passed continuously through the system. To the stirred solution is added dropwise 316 g. (1.90 moles) of triethyl phosphite (Note 3) over a period of 30 minutes, at 110-120°. The mixture is then stirred for 3 hours at 160°. The ethyl bromide evolved is trapped by a condenser and a receiver cooled in an ice bath. The low-boiling... 

Toluenesulfonic acid Bromoacetaldehyde diethyl acetal Sodium periodate Hexamethyldisilazane... 

To a solution of potassium t-butoxide (0.11 mol) in 100 ml DMF was added thiobenzoic acid (0.11 mol) and the solution partially evaporated in vacuo, benzene added in two consecutive portions and evaporated in vacuo each time. To the residual DMF solution was added bromoacetaldehyde diethyl acetal (0.1 mol) and the mixture stirred at 120°C for 15 h. After cooling, it was poured onto water (500 ml), the product extracted with ether, the extract washed with aqueous NaHC03 followed by water, then dried and the solvent removed in vacuo. The residue was distilled in vacuo to give 17.2 g of pure 2-thiobenzoyl acetaldehyde diethyl acetal, boiling point 131-133°C/0.07 mm. 

Our first goal was to develop a scaleable route to the single enantiomer propargylic alcohol. The racemic alcohol was readily produced on a multi-kilogram scale by alkylation of the phenol with inexpensive bromoacetaldehyde diethyl acetal, hydrolysis to the aldehyde, and addition of the acetylenic Grignard reagent. With this material at hand we developed an efficient bioresolution process that esterified the alcohol in the presence of Chirazyme L9 (Scheme 30.7).26 At this point... 

Add bromoacetaldehyde diethyl acetal 11 (313 mL, 410 g, 2.08 mol) to a threenecked round-bottomed flask (2 L) equipped with a magnetic stirrer bar and fitted with a nitrogen inlet, an addition funnel (500 mL) and a still head, condenser and receiver (cooled in an ice bath). Maintain the flask under a gentle... 

Treatment of the aldehyde 19 with amines in the presence of TiCU furnished the precursor 20, which was converted to the 2-pyrrolines 21. The products 21 could thereafter be exposed to methoxide, leading to the corresponding /3-chloropyrroles after elimination of cyanide (Scheme 3) <2005T2879>. A series of pyrroles has also been prepared by a procedure featuring acid-induced cyclization of precursors constructed by sequential lithiation and alkylation of 1-benzylbenzotriazoles with 2-bromoacetaldehyde diethyl acetal and A -benzylideneani-line <1997JHC1379>. 

A protocol involving the intermolecular cyclization between acetals and ureas has been developed to synthesize imidazolones on solid support. Reaction of polymer-bound glycerol 1148 with bromoacetaldehyde diethyl acetal gives the cyclic acetal bromide 1149. Amination followed by urea formation affords the resin-bound urea acetals 1150. The aldehydes released from the resin upon treatment with TFA immediately cyclize to give 2-imidazolones 1151 in good yields and purity (Scheme 279) <2002TL4571>. 

Bromoacetaldehyde diethyl acetal, 492 N-Bromoacetamide, 12,74,985 N-Bromoacetamide-Hydrogen chloride, 74-75... 

Possibly the most frequently used and most widely known phosphonylated aldehyde is diethyl l-formylmethyIphosphonate. A vaiiety of methods for the preparation of this aldehyde are reported in the literature. The oldest employs tlie Michaelis-Arbuzov reaction between triethyl phosphite and bromoacetaldehyde diethyl acetal, which yields diethyl 2,2-diethoxyethylphosphonate on heating to 160°C (Scheme 5.5). Subsequent acid hydrolysis gives diethyl 1-formylmethylphosphonate. The aldehyde function requires protection because it is known that a-haloaldehydcs react with trialkyl phosphites in a Perkow reaction affording dialkyl vinylphosphates isomeric with the expected phosphonates. " ... 

Wardani and Lhomme (93TL6411) used a different pathway for the construction of the pyrrole ring. Base-catalyzed alkylation of N-acetyl-N -tosylproflavine 60 with bromoacetaldehyde diethyl acetal, followed by deprotection of the acetal function with concomitant ring closure and deacylation in acidic media yielded 9-amino-3-tosylpyrrolo[2,3-c]acridine 301. Detosylation was achieved by basic hydrolysis to give 9-aminopyr-rolo[2,3-c]acridine 302 (Scheme 55). 

Paraldehydes are also useful starting materials for synthesis of a>bromo aldehydes. They are first brominated and then converted into their acetals by addition of alcohol.643 High yields (85%) of bromoacetaldehyde diethyl acetal... 

A particularly simple method is to brominate (3 moles of Br2 per mole of paraldehyde) paraldehyde in an alcohol, with vigorous stirring and watercooling, this giving bromoacetaldehyde diethyl acetal (72.5%) and dipropyl acetal (65%),645 also bromoacetaldhyde dibutyl acetal (65%) and diisopropyl acetal (22 %).646... 

Hydroxy-6-methyl-2-pentyl-9-oxo-10-oxa-phenanthrene with bromoacetaldehyde diethyl acetal in refluxing dimethylformamide containing potassium carbonate, after 30 minutes gave the corresponding acetal in 90% yield which by way of the aldehyde obtained upon acidic hydrolysis with 2M hydrochloric acid in 89% yield furnished with ethanolic 0.1M sodium hydroxide during 30 minutes the benzofuran shown in 91% yield (ref.137) a cyclisation attributable to the highly reactive... 

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