Stereocontrolled cyclofunctionalizations of double bonds through heterocyclic intermediates

Cardillo, Giuliana; Orena, Mario

doi:10.1016/s0040-4020(01)81510-6

Cited by 441 publications

(125 citation statements)

References 196 publications

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“…The preference for 5-exo cyclization over 6-endo cyclization observed with substrates 1c and 4b-c, which lack a conjugating substituent on the alkene is typical for a variety of halocyclization reactions (2)(3)(4). Substrates 1a and 4a favor 6-endo cyclization as a result of the greater stability of positive charge localized on benzylic carbons.…”

Section: Discussionmentioning

confidence: 97%

“…1), are versatile synthetic transformations with proven applications to the synthesis of biologically relevant molecules (1)(2)(3)(4)(5)(6). The development of catalytic enantioselective halocyclization methods is a topic of increasing interest in synthetic organic chemistry, one that presents unique challenges and opportunities for various paradigms of catalysis in addition to the obvious importance and utility of this transformation.…”

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confidence: 99%

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Lewis base catalysis of bromo- and iodolactonization, and cycloetherification

Denmark

Burk

2010

Proc. Natl. Acad. Sci. U.S.A.

240

140

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Lewis base catalyzed bromo-and iodolactonization reactions have been developed and the effects of catalyst structure on rate and cyclization selectivity have been systematically explored. The effects of substrate structure on halolactonization reactions and the interaction of those effects with the effects of catalyst structure have been investigated, leading to synthetically useful improvements in cyclization selectivity. The knowledge acquired was applied to the development of Lewis base catalyzed bromoand iodocycloetherification reactions. The ability of some of the surveyed catalysts to influence the cyclization selectivity of halolactonization reactions demonstrates their presence in the transition structure of the product-determining cyclization step. This observation implies that chiral derivatives of these catalysts have the potential to provide enantioenriched products regardless of the rates or mechanisms of halonium ion racemization.halocyclofunctionalization | halogenation E lectrophilic halocyclizations of olefins, in which electrophilic halonium ions are generated from olefins and opened intramolecularly by nucleophilic functional groups (Fig. 1), are versatile synthetic transformations with proven applications to the synthesis of biologically relevant molecules (1-6). The development of catalytic enantioselective halocyclization methods is a topic of increasing interest in synthetic organic chemistry, one that presents unique challenges and opportunities for various paradigms of catalysis in addition to the obvious importance and utility of this transformation. To date, only a few notable successes have been reported; these include the use of chiral Ti-salen complexes in iodoetherification (7) and cinchonidinium phasetransfer catalysts in iodolactonization (8). Recently, modified Cinchona alkaloids have been successfully employed in catalytic enantioselective chlorolactonization (9), as well as a catalytic enantioselective bromolactonization of 1,3-eneynes via conjugate opening of achiral bromonium ions (10-15*).Careful mechanistic studies by Brown and coworkers and from these laboratories identified a serious obstacle to the development of catalytic enantioselective iodination and bromination methods, namely the propensity of iodonium and bromonium ions (but not chloronium ions) to undergo degenerate halogen exchange with olefins ( Fig. 2) (16-19). This process racemizes the halonium ions at rates that can compete with nucleophilic capture. Chiral Lewis base catalysts have the potential to prevent this or other racemization processes, if they remain bound to the halonium ion until the newly created stereocenters are irreversibly set, thus maintaining a chiral environment regardless of exchange. Lewis base catalysis of halogenation has been reported in several different contexts (20-23), as have enantioselective halocyclization reactions promoted by stoichiometric amounts of chiral Lewis bases (13-15), but the paucity of catalytic, enantioselective Lewis base catalyzed halogenations suggests that ...

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Section: Discussionmentioning

confidence: 97%

mentioning

confidence: 99%

Lewis base catalysis of bromo- and iodolactonization, and cycloetherification

Denmark

Burk

2010

Proc. Natl. Acad. Sci. U.S.A.

240

140

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“…1,2 Although, in general, there is a preference for exo-cyclisation, the endo-mode of cyclisation is not precluded. However, in cases where other nucleophilic heteroatoms are present in the precursor, either or both heteroatoms can participate in the cyclisation (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Iodocyclisation of N-allyl ureas; a route to imidazolin-2-ones

Moody¹,

Hunt²,

Smith³

2000

Arkivoc

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“…The results on the cohalogenation of limonene are important because electrophilic additions to it lack stereo The above results led us to investigate the extension of this methodology of cohalogenation with unsaturated monoterpenic alcohols, as a possible route of cyclofunctionalization 21 to produce functionalized bicyclic ethers.…”

Section: Resultsmentioning

confidence: 99%

Cohalogenation of limonene, carvomenthene and related unsaturated monoterpenic alcohols

Sanseverino

Silva

Jones

et al. 2000

J. Braz. Chem. Soc.

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A coalogenação de (R)-limoneno e (R)-carvomenteno com I 2 /H 2 O/Cu(OAc) 2 ·H 2 O em dioxano aquoso seguida por tratamento em meio básico produz estereoespecificamente os transepóxidos correspondentes. Já essa mesma metodologia de coalogenação aplicada a álcoois monoterpênicos insaturados estruturalmente relacionados produz derivados do pinol [a partir de (5R)-cis-carveol e (S)-α-terpineol] ou então iodoidrinas [a partir de (S)-álcool perílico e (5R)-Cohalogenation of (R)-limonene and (R)-carvomenthene with I 2 /H 2 O/Cu(OAc) 2 ·H 2 O in aqueous dioxane followed by base treatment produced stereospecifically the corresponding trans-epoxides. Same methodology of cohalogenation applied to related monoterpenic unsaturated alcohols produced pinol derivatives [from (5R)-cis-carveol and (S)-α-terpineol] or iodohydrins [from (S)-perillyl alcohol and (5R)-trans-carveol].

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Stereocontrolled cyclofunctionalizations of double bonds through heterocyclic intermediates

Cited by 441 publications

References 196 publications

Lewis base catalysis of bromo- and iodolactonization, and cycloetherification

Lewis base catalysis of bromo- and iodolactonization, and cycloetherification

Iodocyclisation of N-allyl ureas; a route to imidazolin-2-ones

Cohalogenation of limonene, carvomenthene and related unsaturated monoterpenic alcohols

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