Woodward reagent K

Structural formula
General
Surname	Woodward reagent K
other names	N -ethyl-5-phenylisoxazolium-3'-sulfonate; 2-Ethyl-5- (3-sulfophenyl) isoxazolium (inner salt);
Molecular formula	C 11 H 11 NO 4 S
Brief description	colorless solid
External identifiers / databases
EC number	223-988-7
ECHA InfoCard	100.021.808
PubChem	77804
Wikidata	Q2593238
properties
Molar mass	253.27 g mol −1
Physical state	firmly
Melting point	207–208 ° C (decomposition)
solubility	good in water (100 g l −1 )
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 302
	P: no P-phrases
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Woodward reagent K is a sulfur-containing heterocyclic organic compound that is present as an inner salt ( zwitterion ). It was named after Robert B. Woodward .

Manufacturing

The reaction of 5-phenylisoxazole with chlorosulfonic acid , subsequent N -alkylation with triethyloxonium tetrafluoroborate and acid hydrolysis gives Woodward reagent K.

use

Carboxylates (RCOO ^- ) react with Woodward's reagent K under very mild reaction conditions to form reactive enol esters that are used in peptide synthesis . The carboxylate group is a N -protected amino acid or an N -protected peptide with the Woodward reagent K in the presence of triethylamine activated . It is then reacted with an amino acid ester hydrochloride or a peptide ester hydrochloride in the presence of an equivalent of triethylamine, a new peptide bond being formed. This creates N -protected peptide esters.

Individual evidence

↑ ^a ^b ^c ^d Data sheet Woodward reagent K from Sigma-Aldrich , accessed on November 3, 2016 ( PDF ).
^ The Merck Index. An Encyclopaedia of Chemicals, Drugs and Biologicals. 14th edition, 2006, p. 1731, ISBN 978-0-911910-00-1 .
↑ ^a ^b R. B. Woodward, RA Olofson, Hans Mayer: A new Synthesis of Peptides. In: Journal of the American Chemical Society. 83, 1961, pp. 1010-1012. doi : 10.1021 / ja01465a072 .

[sigma-1] Data sheet Woodward reagent K from Sigma-Aldrich , accessed on November 3, 2016 ( PDF ).

[MerckIndex-2] The Merck Index. An Encyclopaedia of Chemicals, Drugs and Biologicals. 14th edition, 2006, p. 1731, ISBN 978-0-911910-00-1 .

[Woodward-3] R. B. Woodward, RA Olofson, Hans Mayer: A new Synthesis of Peptides. In: Journal of the American Chemical Society. 83, 1961, pp. 1010-1012. doi : 10.1021 / ja01465a072 .