Ni–Pd Catalyzed Cyclization of Sulfanyl 1,6-Diynes: Synthesis of 1′‑Homonucleoside Analogues

The Ni–Pd catalyzed addition–cyclization of sulfanyl 1,6-diynes <b>2</b>–<b>9</b> with nucleobases is described. The reactions of <i>N</i>-tethered 1,6-diynes with <i>N</i>³-benzoylthymine, <i>N</i>⁴,<i>N</i>⁴-bis­(Boc)­cytosine, <i>N</i>³-benzoyluracil and <i>N</i>⁶,<i>N</i>⁶-bis­(Boc)­adenine exclusively afforded the pyrrolylmethyl and furylmethyl nucleotides in good yields. Deprotection of nucleobases was completed by treatment with acids or bases. Furthermore, the reactions of pyrroles and furans with nucleophiles such as alkoxides and amines underwent detosylation and conversion to the alkoxymethyl- and arylaminomethyl-pyrroles and furans in good yields

Synthesis of Azepines via a [6 + 1] Annulation of Ynenitriles with Reformatsky Reagents

A protocol for the direct synthesis of azepines using a hafnium­(III)-catalyzed [6 + 1] annulation of N-tethered ynenitriles with Reformatsky reagents is reported. A broad range of 3-amino-2,7-dihydro-1<i>H</i>-azepine-4-carboxylates <b>4aa</b>–<b>4he</b> were obtained in high yields and with excellent functional group tolerance. The copper-mediated reactions of isolable Blaise intermediates (enamino esters <b>3</b>), uniquely underwent 5-endo cyclization to afford the β-2,5-dihydropyrrolyl α,β-unsaturated esters <b>5aa</b>–<b>5fc</b>, which exhibit anticancer activity