Synthesis and Diels-Alder reactivity of chiral 2-(alk-1-enyl)-1,3,2-diazaphospholidine 2-oxides

✍ Scribed by Peter B. Wyatt; Carolina Villalonga-Barber; Majid Motevalli

• Book ID: 104260689
• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 245 KB
• Volume: 40
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(98)80044-0

✦ Synopsis

2-(AIk-l-enyl)-l,3,2-diazaphospholidine 2-oxides 4, containing the trans-N,N'-dihenzylcyclohexane-l,2diamine chiral auxiliary, may he prepared by palladium(0)-mediated coupling of the phosphorous acid derivative 3 with alkenyi halides. The X-ray crystal structure of the prop-l-enyl compound 4b has been determined. Some stereoselectivity has been obselxed in Diels-Alder reactions of the compounds 4. For example, the substituted (E)acrylate ester 4e acts as a dienophile towards cyclopentadiene in hot toluene to give the four possible diastereoisorneric adducts in a 62:17:15:6 molar ratio; it has been shown that the structure of the main product Se is consistent with attack of the diene on the less hindered face of the dienophile and that the methoxycaflxmyl, rather than the diazaphospholidinyl group, has the endo-orientation. The dienyl-1,3,2-diazaphospholidine 2-oxide 41' acts as a diene in the reaction with 4-phenyl-1,2,4-triazoline-3,5-dione to give a 70:30 mixture of adducts.