Tributylphosphine , Mitsunobu reaction

Alternatively, alkyl aryl ethers can be prepared from support-bound aliphatic alcohols by Mitsunobu etherification with phenols (Table 7.13). In this variant of the Mit-sunobu reaction, the presence of residual methanol or ethanol is less critical than in the etherification of support-bound phenols, because no dialkyl ethers can be generated by the Mitsunobu reaction. For this reason, good results will also be obtained if the reaction mixture is allowed to warm upon mixing DEAD and the phosphine. Both triphenyl- and tributylphosphine can be used as the phosphine component. Tributyl-phosphine is a liquid and generally does not give rise to insoluble precipitates. This reagent must, however, be handled with care because it readily ignites in air when absorbed on paper. 

The p-sulfanyl amides 28 are synthesized from N-protected amino acids 24 via amino alcohols 25, which are converted into (5-acetylsulfanyl amides 26 by a Mitsunobu reaction. The (5-amine disulfide 27 is subsequently coupled with a variety of carboxylic acids, followed by reduction with tributylphosphine in aqueous THF in the presence of pyridine to produce the free thiol 28 (Scheme 5).1211 Detailed experimental procedures for these compounds have not been reported. 

Diacetoneglucose has been used in a study of the mechanism of the Mitsunobu reaction with tributylphosphine in place of the usual triphenylphosphine. ... 

In solution, phase amino acid derived methyl ester N-Fmoc-Tyr-OMe 4 was successfully condensed under Mitsunobu conditions with 2,3,4,6-tetra-Oacetyl-D-glucose 2 to afford the fully protected glucosylamine 5. The reaction provides products of analytical purity and predictable stero-chemistry, as confirmed by H/ C NMR. Synthetic conditions and protective groups for glycopeptides synthesis have been investigated. Mitsunobu conditions employed in solution phase are based on the improved redox system l,l -azodicarbonyldipiperidine (ADDP)—tributylphosphine (TBP) in... 

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