Investigations into a mild Diels-Alder approach to 6-substituted quinazoline-2,4-dione derivatives

Abstract

1.42 mL) was stirred at 0 °C for 1.5 h. After addition of brine (2 mL), the mixture was extracted with ethyl acetate (3X3 mL).The combined organic extracts were washed with brine, dried, and evaporated. The residue was purified by chromatography to yield 23 (57 mg, 65%) as an oil:-2.29°(c 1.245, CHC13); IR (neat) 3460, 1720, 1710,1660 cm'1; NMR (CdCl3) S 1.46 (s, 9 H), 2.38-2.42 (m, 2 H), 2.99 (br s, 1 H), 3.72 (s, 3 H), 3.58-3.76 (m, 2 H), 3.82-4.07 (m, 2 H), 5.41 (d, J = 9.0 Hz, 1 H), 5.92 (d,

Me2(CH2CH)SiCN: a bifunctional ethylene equivalent for Diels–Alder reaction based controllable tandem synthesis

“… 2 Usually, DA reactions proceed smoothly when the dienophiles are activated by electron-withdrawing groups. When it comes to cycloaddition of ethylene, which is a commonly required synthetic step, the conditions entail very high temperature and pressure, 3 which are often too harsh to be used easily ( Scheme 1a ). Therefore, the development of ethylene equivalents that can be used for DA reactions under milder conditions has received great attention.…”