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1.
J Am Chem Soc ; 126(39): 12432-40, 2004 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-15453777

RESUMO

The first enantioselective total synthesis of (+)-brasilenyne (1) has been achieved in 19 linear steps, with 5.1% overall yield from l-(S)-malic acid. The construction of the oxonin core containing a 1,3-cis,cis diene unit was accomplished with a tandem ring-closing metathesis/silicon-assisted intramolecular cross-coupling reaction. In addition, a key propargylic stereogenic center was created through a novel, highly diastereoselective ring opening of a 1,3-dioxolanone promoted by TiCl(4). This reaction proceeded through an oxocarbenium ion intermediate and the asymmetric induction was fully controlled by l-malic acid residue. The C(8) stereogenic center was set by a reagent-controlled asymmetric allylboration.


Assuntos
Éteres Cíclicos/síntese química , Silício/química , Alcinos/química , Cobalto/química , Cristalografia por Raios X , Dioxolanos/química , Éteres/química , Éteres Cíclicos/química , Malatos/química , Compostos Organometálicos/química , Estereoisomerismo
2.
J Am Chem Soc ; 124(51): 15196-7, 2002 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-12487594

RESUMO

The first, total synthesis of (+)-brasilenyne (1) has been achieved in 19 steps from l-(S)-malic acid. The key elements of this approach are a highly diastereoselective ring-opening of a 1,3-dioxolanone with bis(trimethylsilyl)acetylene) promoted by TiCl4 to set a propargylic stereocenter and the successful application of the sequential ring closing metathesis/silicon-assisted intramolecular cross-coupling reaction for construction of the oxonin core structure of 1.


Assuntos
Éteres Cíclicos/síntese química , Silício/química , Animais , Aplysia/química , Estereoisomerismo
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