Rink Acid resins
Rink acid resins are super acid-labile supports for the solid phase immobilization of carboxylic acids. Cleavage can be effected with as little as 10% AcOH in DCM, providing highly acid-sensitive products in high yields and purities. However, care must be taken to prevent product loss during synthetic manipulations, owing to the extreme acid sensitivity of this support.
Treatment with HCl in THF or Ph3PCl2 has been shown to efficiently convert this resin to the corresponding benzhydryl chloride, to which can be coupled a wide range of functional groups: hydroxylamines; alcohols, amines, acids and thiols.
Rink acid resin has also been converted to a trifluoroacetate with TFA and used in a similar manner to immobilize amines, thiols, alcohols, and phenols.
Cleavage of amines and alcohols from this support has been carried out with either 5% TFA in DCM or 20% TFA in DCM; thiols were released with either 5% TFA in DCM or 95% aq. TFA.