نتایج جستجو برای: mitsunobu
تعداد نتایج: 201 فیلتر نتایج به سال:
Aerobic recycling: A catalytic amount of a hydrazine reagent is sufficient to promote Mitsunobu reactions in the presence of triphenylphosphine, an iron catalyst, and air. The active form of the catalyst, an azo species, can be readily generated by iron-catalyzed aerobic oxidation. MS = molecular sieves, Pc = phthalocyanine.
The title compound, C(20)H(25)NO(4), was synthesized by a Mitsunobu reaction of sinomenine [(9S,13R,14R)-7,8-didehydro-4-hydroxy-3,7-dimethoxy-17-methylmorphinan-6-one] with methanol. The chiral centers were unchanged during the reaction. Intra-molecular C-H⋯O hydrogen bonds result in the formation of six-membered rings.
A series of new cyclohexenyl nucleosides is synthesized by coupling the heterocyclic bases with a protected cyclohexenyl precursor under Mitsunobu conditions. The compounds were evaluated for their antiviral and cytostatic activity. Pronounced activity against herpes simplex virus type 1 and type 2 was observed for the 2,6-diaminopurine analogue.
A rapid urea radiolabelling methodology has been developed. [(11)C]CO2 was activated by 1,8-diazabicycloundec-7-ene (DBU) in the presence of aliphatic and aromatic amines and reacted with Mitsunobu reagents to produce asymmetric (11)C radiolabelled ureas in high radiochemical yields.
A highly regioselective SN2' Mitsunobu reaction between Morita-Baylis-Hillman (MBH) alcohols, azodicarboxylates, and triphenylphosphine is developed, which provides an easy access to α-alkylidene-β-hydrazino acid derivatives in high yields and good stereoselectivity. This reaction represents the first direct transformation of MBH alcohols into hydrazines.
The sulfamide functional group is increasingly relevant in both medicinal and bioorganic chemistry. We report here practical access to a series of N2,N5-substituted five-membered cyclosulfamides. The five-membered heterocyclic motif was prepared starting from proteogenic amino acids and chlorosulfonyl isocyanate via the Mitsunobu reaction. Selected chemical and spectral proprieties and the anti...
Di-p-chlorobenzyl azodicarboxylate (DCAD) is introduced as a novel, stable, solid alternative to DEAD and DIAD for a variety of Mitsunobu couplings. DCAD/Ph(3)P-mediated reactions in CH(2)Cl(2) generate a readily separable hydrazine byproduct. [reaction: see text]
An operationally simple protocol for the synthesis of 2,3-dihydrobenzo[f][1,4]oxazepin-3-ones, based on an Ugi reaction of an ortho-(benzyloxy)benzylamine, glycolic acid, an isocyanide and an aldehyde, followed by an intramolecular Mitsunobu substitution was developed. The required ortho-(benzyloxy)benzylamines have been in situ generated from the corresponding azides, in turn prepared in high ...
An enantioselective total synthesis of the cytotoxic latrunculin congener (+)-18-epi-latrunculol A has been achieved. Key steps in the synthetic route include an acid-mediated enone cyclization/equilibration sequence, a Carreira alkynylation, and a late-stage Mitsunobu macrolactonization to construct the macrolide skeleton.
Various Mitsunobu conditions were investigated for a series of flavonolignans (silybin A, silybin B, isosilybin A, and silychristin A) to achieve either selective esterification in position C-23 or dehydration in a one-pot reaction yielding the biologically important enantiomers of hydnocarpin D, hydnocarpin and isohydnocarpin, respectively. This represents the only one-pot semi-synthetic metho...
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