Mild generation of o-quinodimethanes via fluoride induced 1,4-elimination of α-(o-trimethylsilylmethyl)benzylesters: stereoselective synthesis of 19-nor steroids and RU486 precursors
作者:Marc Port、Robert Lett
DOI:10.1016/j.tetlet.2006.04.129
日期:2006.7
19-Nor steroids and RU486 tricyclic synthetic intermediates were stereoselectively prepared by an intramolecular Diels–Alder reaction involving an o-quinodimethane possessing a pro-17 unique chiral stereocenter, substituted by a protected hydroxyl group. The o-quinodimethane was generated in mild conditions by fluoride induced 1,4-elimination of α-(o-trimethylsilylmethyl)benzylesters and the present
19-Nor类固醇和RU486三环合成中间体是通过分子内Diels-Alder反应立体选择性地制备的,该反应涉及具有一个亲-17独特手性立体中心的邻喹啉甲烷,并被一个受保护的羟基取代。所述Ô -quinodimethane由α-(氟化诱导1,4-消除在温和条件下产生ö -trimethylsilylmethyl)苄基酯,并且本方法允许以α一个灵活的接入,α'二取代ö-quinodimethanes,如11β-取代的类固醇方法所示。本文报道的IMDA非对映选择性高度依赖于羟基保护基的性质和优于通过相应的苯并环丁烯的热解所观察到的非对映选择性。