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Applications of the (PhO)(3)PCl2 reagent: A new protocol for mild cleavage of sulfinamides and sulfonamides
No full textThe triphenyl phosphite-chlorine reagent, freshly in situ prepared by the action of chlorine on a solution of triphenyl phosphite in dichloromethane, is successfully used in the cleavage of both sulfonamides and sulfonamides under extremely mild conditions (-15 degrees C to r.t.). Final amines are easily recovered by a simple acid/base extraction, and no further purification is required
Stereoselective Total Synthesis of (–)-Microcarpalide, a Novel Fungal Metabolite Targeting Actin Microfilament
No full text
Total synthesis of )-microcarpalide, a novel microfilament disrupting metabolite
No full textThe stereoselective total synthesis of (-)-microcarpalide, a recently discovered 10-membered lactone of fungal origin displaying a remarkable disrupting action on actin micro. laments, was accomplished by using ring-closing metathesis (RCM) as the key step for the formation of the medium-sized ring. The diene ester required for the macrocyclization reaction was assembled via DCC-mediated esterification of two suitable partners, each bearing a terminal alkene group. The alcohol fragment was synthesized from n-bromohexane through a seven-step sequence entailing two consecutive stereoselective homologations of chiral boronic esters as strategic transformations for the sequential insertion of the two stereocentres with the final S absolute configuration, using (+)-pinanediol as the chiral director; final elaboration to the desired C-11 framework envisaged treatment with an allyl Grignard reagent and oxidative cleavage of the boronic scaffold. In contrast, the acidic fragment was prepared in ten steps from D-tartaric acid, whose C-4 backbone was elongated to the required C-7 skeleton by means of two distinct Swern-Wittig oxidation - homologation sequences
A mild synthesis of nitriles by TPPX2-promoted dehydration of primary amides
No full textAn expeditious route to nitriles via dehydration of primary amides using halotriphenoxy phosphonium halides (TPPX2, X = Cl or Br) is described. The reaction proceeds under very mild conditions and allows the preparation of aromatic and aliphatic nitriles in good to excellent yields
A mild synthesis of nitriles by von Braun degradation of amides using triphenyl phosphite-halogen-based reagents
No full textA mild procedure for the synthesis of aromatic and aliphatic nitriles is disclosed. In the presence of bromotriphenoxyphosphonium bromide (TPPBr2), N-alkyl and N,N-dialkyl amides undergo von Braun degradation to nitriles in good to excellent yields under the mildest conditions ever reported. The reaction proceeds via formation of an iminoyl bromide intermediate at –60 °C, which subsequently dealkylate upon refluxing in chloroform or even at r.t. In the case of N-tert-butyl, N-α-phenylethyl and N-benzhydryl amides, chlorotriphenoxyphosphonium chloride (TPPCl2) generated at –30 °C was also effective
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