%0 Journal Article
%T Development of new chiral auxiliary from the Diels-Alder adduct endo-tricyclo[6.2.1.02,7] undeca-4 ,9-dien-3 ,6-dione Desenvolvimento de novos auxiliares de quiralidade a partir do aduto de Diels-Alderendo-triciclo[6.2.1.02,7]undeca-4,9-dien-3,6-diona
%A Su¨¦ly Copini
%A Fel¨ªcia Megumi Ito
%A Camila C. Ungari
%A D¨ºnis P. Lima
%J Orbital : the Electronic Journal of Chemistry
%D 2012
%I Universidade Federal de Mato Grosso do Sul
%X Stereochemistry control is very important in organic synthesis and it is a basic challenge in asymmetric synthesis. An approach widely used is making use of chiral auxiliary compounds. In this work it is showed the synthesis of highly optically pure rigid polycyclic compounds from the Diels-Alder adduct 1. Compounds 1-3 were prepared as described by Ito et. al. [1]. The alcohol (-)-3 was obtained by biotransformation of diketone 2 with Mucor ramosissimus, e.e.>99% (60%). The polycyclic halides 4-6 were synthesized (60-97%) after treatment of alcohol (-)-3 with NBS, NIS and, NCS in dichloromethane, respectively. Compound 7 was prepared by reaction with p-toluenesulfonic acid, whilst 8 was prepared by treatment of (-)-3 with m-chloroperbenzoic acid. The strained polycylic alcohols 9-13 will be achieved by reduction of ketones 4-8 with NaBH4. All compounds were identified by 1H and 13C NMR spectroscopy. Due to intrinsic rigidity of the synthesized polycyclic, they could be of use as chiral auxiliary agents. Prochiral substrates can be readily attached by many ways to C-3 or through hydroxyl group found in compounds 8-13. The stereo-dirigent potential of these polycyclic can also be increased by directly or indirectly introduction of many groups at position C-3, or at adjacent positions to carbonyl or hydroxyl at C-3 and C-10. Controle estereoqu¨ªmico ¨¦ muito importante em s¨ªntese organica e se constitui no desafio b¨¢sico da s¨ªntese assim¨¦trica. Uma abordagem amplamente utilizada ¨¦ o emprego de auxiliares de quiralidade. Neste trabalho apresentamos a s¨ªntese de compostos polic¨ªclicos r¨ªgidos com alta pureza ¨®ptica a partir do aduto de Diels-Alder 1. Os compostos 1-3 foram preparados de acordo com Ito et. al.1. O ¨¢lcool (-)-3 foi obtido por biotransforma  o da dicetona 2 utilizando o fungo Mucor ramosissimus, com e.e. >99% (rendimento: 60%). Os haletos pol¨ªclicos 4-6 foram obtidos com rendimentos significativos (60-97%), ap¨®s tratamento do ¨¢lcool (-)-3 com NBS, NIS e NCS em diclorometano, respectivamente. O composto 7 foi preparado em acetato de etila na presen a de ¨¢cido p-toluenossulf nico, enquanto que 8 foi obtido pela tratamento de (-)-3 com ¨¢cido m-cloroperbenz¨®ico. Os alco¨®is polic¨ªclicos r¨ªgidos 9-13 ser o obtidos ap¨®s redu  o das cetonas 4-8 com NaBH4. Todos os compostos sintetizados foram identificados por espectroscopia de RMN de 1H e de 13C. Devido ¨¤ rigidez inerente dos policiclos sintetizados, estes poder o ser utilizados como auxiliares de quiralidade. Substratos pr¨®-quirais podem ser prontamente ligados por v¨¢rios meios em C-3 ou atrav¨¦s da hi
%K Diels-Alder
%K biotransforma  o
%K auxiliares de quiralidade
%U http://www.orbital.ufms.br/index.php/Chemistry/article/view/350