BARBIER - WIELAND Degradation

Barbier-Wieland degradation A method for the stepwise degradation of aliphatic acids... 

BARBIER - WIELAND Degradation A multi-step procedure tor chain degradation ot esters... 

Cholic acid may be converted in several steps into the 3,9-epoxy-carboxyIic acid (246) which has the ABC ring system of batrachotoxin. The synthesis of 24-nor-5a-cholic acid from methyl cholate involved the Barbier-Wieland degradation of the side-chain and treatment of the resultant 24-nor-5/3-cholic acid with Raney nickel. A major product of this reaction was the 5a-3-oxo-compound (247) which... 

Barbier-Wieland Degradation (Barbier-Locquin Degradation)... 

Subsequent exposure of geminal dibromide 62 to BU3S11H provided the desired ester 63 via a stereocontrolled cyclization-debromination tandem sequence. Finally, Barbier-Wieland degradation and hydrogenolytic debenzylation of ester 63 afforded 5a-carba-D-fructofuranose 64 in excellent yields. In a preliminary enzymological study, its 6-phosphate derivative showed to be an interesting substrate for the enzymes of the glycolysis pathway. 

Bam mane ware, 25, 72, 97 Barbier Wieland, degradation of carboxylic acid by method of, 24,38,41 Barbituric acid, 21, 5 Barium carbonate, 22, 86 Barium chloride, 23, 17 Barium hydroxide, 22, 87, 91, 25, 75, 27, 1... 

Several compounds are best prepared by this reaction, although it has been used chiefly for proof of organic structure. The Barbier-Wieland degradation is a classical method for the removal of one carbon atom from a chain. 

Barbier-Wieland degradation, 420 Barium salts of acids, decarboxylation, 331... 

Barbier-Wieland degradation Boudroux-Chichibabin synthesis Bouveault aldehyde synthesis Darzens synthesis Friedel-Crafts Reaction Gatterman-Koch reaction Grignard reaction Reformatsky reaction Saytzeff reaction Ullmann coupling reaction Wiirtz coupling reaction Wiirtz-Fittig reaction... 

Synthesis from Steroidal and Alkaloidal Intermediates Steroidal intermediates have been employed in the synthesis of certain alkaloids such as dihydroconessine (58)(ref.55), one of the 3-aminoconanine bases, from the bile acid compound 3-B-acetoxybisnorcholenic acid, a substance obtained from appropriately-protected coprostanol by oxidation and two Barbier-Wieland degradations. The method consisted in converting the carboxyl into a formylamino group, the acetoxy into a tosylate which was then substituted by a dimethylamino group, reduction of the formylamino to methylamino and formation of the five-membered ring E by... 

Barbier-Wieland degradation. Stepwise carboxylic acid degradation of aliphatic acids (particularly in sterol side chains) to the next lower homo log. The ester is converted to a tertiary alcohol that is dehydrated with acetic anhydride, and the olefin oxidized with chromic acid to a lower homologous carboxylic acid. 

The ketonisation of higher olefins is possible without any problems, if the C = C-bond is a terminal one so 1-octene can be converted to 2-octanon and 10-undecenoic acid to 10-oxo-undecanoic acid [24, 25], The direct ketonisation of 9-decenoic acid, however, not prepared by olefin metathesis but by Barbier-Wieland-degradation of 10-undecenoic acid, has been reported, too [26],... 

A fairly straightforward scheme, called the Barbier-Wieland degradation, was at that time used for determining the number of carbon atoms in an ahphatic acid fragment. This involves first converting the carboxylic acid 11-1 to the corresponding ester 11-2 (Scheme 1.11). Reaction of the ester with phenylmagnesium bromide leads to carbinol 11-3. Treatment with acid leads to dehydration and formation of the olefin 11-4. Oxidation by one of several methods cleaves... 

Carboxylic acids from ethylene derivatives Barbier-Wieland degradation of bile acids... 

Barbier-Wieland degradation of steroid carboxylic acids Ethylene derivatives from carboxylic acids... 

BAMBERGER Benzotnazine synthesis 17 BAMFORD - STEVENS CAGLIOTI - SHAPIRO Reaction 18 BARBIER Reaction 19 BARBIER - WIELAND Degradation 20 BART SCHELLER Arsonyfation 21 BARTON Name photolysis 22 BARTON Deamination 23 BARTON Decarboxylation 24... 

---