نتایج جستجو برای: claisen rearrangement
تعداد نتایج: 27614 فیلتر نتایج به سال:
2,2,5-Trisubstituted pyrrolidines are available from allylic pyroglutamates by Ireland-Claisen ester rearrangement followed by Eschenmoser sulfide contraction and reduction in a highly diastereoselective and efficient sequence. Some of the products from this sequence exhibit activity against S. aureus, but are much less active against E. coli.
[structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nit...
The synthesis of dehaloperophoramidine, a non-halogenated derivative of the marine natural product perophoramidine, and its biological activity towards HCT116, HT29 and LoVo colorectal carcinoma cells is reported. A [3,3]-Claisen rearrangement and an epoxide opening/allylsilylation reaction installed the contiguous all-carbon quaternary stereocentres with the required relative stereochemistry.
The Claisen rearrangement of sugar derived allyl vinyl ether, Wittig olefination and intramolecular acetalization reactions were used as key steps in the first stereoselective total synthesis of neosemburin and isoneosemburin through the formation of a 3-C-branched sugar precursor as a key intermediate.
[reaction: see text] Two different routes to the tricyclic core of Garcinia-derived natural products are described. The first approach is based on a tandem Claisen/Diels-Alder rearrangement and delivers the desired lactone 14. The second approach, employing a Wessely oxidation/Diels-Alder protocol, leads to the same caged heterocycle, albeit with modified constitution.
Intricate caged molecular frameworks are assembled by an atom economical process via a Diels-Alder (DA) reaction, a Claisen rearrangement, a ring-closing metathesis (RCM) and an alkenyl Grignard addition. The introduction of olefinic moieties in the pentacycloundecane (PCUD) framework at appropriate positions followed by RCM led to the formation of novel heptacyclic cage systems.
Illisimonin A is a new sesquiterpene isolated from Illicium simonsii, and it possesses novel 5/5/5/5/5 pentacyclic skeleton. The tricyclic skeleton of illisimonin A, tricyclo[5.2.1.01,5]decane, presumed to be biosynthesized allo-cedranes via skeletal rearrangement. Herein, we report the concise synthesis highly oxidized by an intramolecular Diels–Alder reaction using ortho-benzoquinones demonst...
1,1-Divinyl-2-phenylcyclopropanes are entry points to a rich area of rearrangement chemistry. With N,N-diallyl amide substrates, tandem radical cyclizations can be initiated at room temperature. Warming provides products of pure thermal rearrangements with acids, ester, and amides. These isomerizations give vinylcyclopentenes resulting from divinylcyclopropane rearrangements and more deeply rea...
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