Suzuki reaction of vinyl triflates from six- and seven-membered N-alkoxycarbonyl lactams with boronic acids and esters.
The Pd(0)-catalyzed reaction of vinyl triflates from N-alkoxycarbonyl lactams with different boron compounds has been studied. The coupling reaction of alkenylboronates and arylboronic acids with six- and seven-membered lactam-derived N-alkoxycarbonyl vinyl triflates was feasible under very mild conditions in THF-water employing (Ph3P)2PdCl2 as a catalyst and Na2CO3 as a base, which provided in high yields the corresponding 6- or 7-substituted N-alkoxycarbonyl-3,4-dihydro-2H-pyridines and N-alkoxycarbonyl-2,3,4,5-tetrahydroazepines. Allylboronates reacted slower but, with vinyl triflates from delta-valerolactam, still gave acceptable yields of the coupling product. Alkylboronic acids required different reaction conditions, in particular the presence of Ag2O together with a base in anhydrous toluene and (dppf)PdCl2 as a catalyst, affording the corresponding 6-alkyl-N-alkoxycarbonyl-3,4-dihydro-2H-pyridines in high yields.
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Dipartimento di Chimica Organica U. Schiff and Centro di Studio sulla Chimica e la Struttura dei Composti Eterociclici e loro Applicazioni, CNR, Università di Firenze, Via G. Capponi 9, I-50121 Firenze, Italy. occhito@chimorg.unifi.it
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