Synthesis of Bridgehead Halides by Barton Halodecarboxylation

1989 ◽  
Vol 42 (1) ◽  
pp. 61 ◽  
Author(s):  
EW Della ◽  
J Tsanaktsidis
Keyword(s):  
Carbon Tetrachloride ◽  
Carboxylic Acids ◽  
Sodium Salt ◽  
Acid Chloride ◽  
Bromine Atom

Bridgehead carboxylic acids can be converted into their corresponding chlorides very efficiently under Barton halodecarboxylation conditions. Addition of the acid chloride to a suspension of the sodium salt of 1-hydroxypyridine-2(1H)- thione in boiling carbon tetrachloride under irradiation leads to excellent yields of the bridgehead chloride via the derived thiohydroxamic ester. In a useful modification for the synthesis of volatile halides, either 1,1,1-trichloro-2,2,2-trifluoroethane or trichlorofluoromethane can be employed as substitute solvents. It is found that the Barton procedure is applicable to the synthesis of labile bromides such as 1-bromobicyclo[3.1.1]heptane for which the usual Hunsdiecker reaction fails. For these, and other brominations , 2-bromo-2-chloro-1,1,1-trifluoroethane ('Halothane') is shown to function as an efficient solvent/bromine atom donor.

CORRELATION OF O–H STRETCHING FREQUENCIES WITH pK VALUES FOR SOME PHENOLS

1957 ◽  
Vol 35 (12) ◽  
pp. 1555-1560 ◽  
Author(s):  
P. M. G. Bavin ◽  
William J. Canady
Keyword(s):  
Carbon Tetrachloride ◽  
Carboxylic Acids ◽  
Carbon Disulphide ◽  
Substituted Phenols ◽  
Electrostatic Effects ◽  
Single Straight Line ◽  
Linear Relationships ◽  
Straight Line ◽  
Alcohol Water

The O–H stretching frequencies, in carbon disulphide, of a number of phenols have been determined. Linear relationships were observed on plotting the stretching frequency against pKA in water. Polar substituted phenols were found to fall along one line, while phenols substituted with aliphatic groups were found to fall along another line of different slope. A change of slope is observed when the stretching frequencies of phenols are plotted against pKA measured in alcohol–water mixtures.Using Goulden's O–H stretching frequencies of carboxylic acids measured in carbon tetrachloride, an attempt has been made to explain the observed deviations from a single straight line in terms of electrostatic effects in the ionizing solvent. The results indicate that for the substances examined, such effects are not responsible for the observed deviations.

scholarly journals Elongated and substituted triazine-based tricarboxylic acid linkers for MOFs

2016 ◽  
Vol 12 ◽  
pp. 2267-2273 ◽  
Author(s):  
Arne Klinkebiel ◽  
Ole Beyer ◽  
Barbara Malawko ◽  
Ulrich Lüning
Keyword(s):  
Nitro Group ◽  
Carboxylic Acids ◽  
Functional Groups ◽  
Acid Chloride ◽  
Methoxy Group ◽  
Suzuki Coupling ◽  
Tricarboxylic Acid

New triazine-based tricarboxylic acid linkers were prepared as elongated relatives of triazinetribenzoic acid (TATB). Additionally, functional groups (NO2, NH2, OMe, OH) were introduced for potential post-synthetic modification (PSM) of MOFs. Functionalized tris(4-bromoaryl)triazine “cores” (3a,3b) were obtained by unsymmetric trimerization mixing one equivalent of an acid chloride (OMe or NO2 substituted) with two equivalents of an unsubstituted nitrile. Triple Suzuki coupling of the cores 3 with suitable phenyl- and biphenylboronic acid derivatives provided elongated tricarboxylic acid linkers as carboxylic acids 17 and 20 or their esters 16 and 19. Reduction of the nitro group and cleavage of the methoxy group gave the respective amino and hydroxy-substituted triazine linkers.

THE PHOTOINITIATED HALOGENATION REACTIONS OF N-BROMOACETANILIDE AND N-BROMO-2,4,6-TRICHLOROACETANILIDE

1966 ◽  
Vol 44 (13) ◽  
pp. 1555-1562
Author(s):  
Dennis D. Tanner ◽  
Eugene Protz
Keyword(s):  
Carbon Tetrachloride ◽  
Bromine Atom ◽  
Benzyl Bromide ◽  
Chain Process ◽  
Chain Mechanism ◽  
Chain Component ◽  
Rearrangement Reaction ◽  
A Chain ◽  
Photoinduced Rearrangement ◽  
Long Chain

The photoinduced rearrangement reaction of N-bromoacetanilide to p-bromoacetanilide in carbon tetrachloride was found to have a quantum efficiency approaching unity, and evidence is presented to indicate a chain component to the reaction process whose product-determining species is either the mesomeric acetanilide radical or the bromine atom. It was demonstrated that small variations in the solvent composition affected the product ratio of p- to o-bromoacetanilide. The reaction of N-bromoacetanilide in carbon tetrachloride with added toluene was found to be a long-chain process producing p-bromoacetanilide as well as acetanilide and benzyl bromide. The bromination of toluene by N-bromo-2,4,6-trichloroacetanilide was shown to proceed by a chain mechanism involving the bromine radical as the chain-propagating species, and this mechanism is used as a model to explain the reaction of N-bromoacetanilide in dilute carbon tetrachloride solutions of toluene.

Ribonucleosides of 3-amino- and 3,5-diaminopyrazole-4-carboxylic acid and their open-chain analogues: Synthesis and reactions

1986 ◽  
Vol 51 (7) ◽  
pp. 1512-1531 ◽  
Author(s):  
Maria K. Spassova ◽  
Antonín Holý ◽  
Milena Masojídková
Keyword(s):  
Carboxylic Acid ◽  
Acid Hydrolysis ◽  
Carboxylic Acids ◽  
Sodium Salt ◽  
Alkaline Hydrolysis ◽  
Trimethylsilyl Derivative ◽  
Open Chain ◽  
Silyl Derivatives ◽  
Hydrolysis Of

Bis(trimethylsilyl) derivative of ethyl 3-aminopyrazole-4-carboxylate (VI) and tris(trimethylsilyl) derivative of ethyl 3,5-diaminopyrazole-4-carboxylate (VII) on reaction with 2,3,5-tri-O-benzoyl-D-ribofuranolyl chloride and subsequent debenzoylation afforded the respective β-D-ribofuranosyl derivatives VIIIa and Xa. Their alkaline hydrolysis led to 1-(β-D-ribofuranosyl)-3-aminopyrazole-4-carboxylic acid (VIIIc) and 1-(β-D-ribofuranosyl)-3,5-diaminopyrazole-4-carboxylic acid (Xb). The esters VIIIa and Xa were not ammonolyzed under normal conditions. Contrary to nucleosidation of the silyl derivatives VI and VII, sodium salt of ethyl 3-aminopyrazole-4-carboxylate was alkylated with 4-chloromethyl-2,2-dimethyl-1,3-dioxolane (XI) or 5-(p-toluenesulfonyloxy)-1,3-dioxane (XVIIb) to give a mixture of the N-isomeric derivatives XIIIa, XIXa and XIIa, XVIIIa, respectively; sodium salt of the 3,5-diamino derivative V reacted with these synthons under formation of the corresponding compounds XIIIb and XXa. Subsequent alkaline and acid hydrolysis of XIIa and XIIIb gave the open-chain analogs of nucleosides XV and XVI. The N-(1,3-dioxan-5-yl) derivatives XVIIIc and XXa resisted acid hydrolysis, giving rise only to carboxylic acids XVIIIb and XXb.

Sign in / Sign up

Export Citation Format

Share Document