Organoytterbium Ate Complexes Extend the Value of Cyclobutenediones as Isoprene Equivalents

摘要

3-Methyl-4-methoxycyclobuten-1,2-dione (la) has long been recognized as a valuable isoprene equivalent in natural products total synthesis, particularly for the preparation of hydroquinones, quinones, and their benzannulated analogues (e.g. Scheme 1).It is readily introduced to a substrate as the electrophilic component in organolithium or Grignard addition reactions, for example, 1a —>2. Here, the differential reactivity of the C1 and C2 carbonyl groups in 1 a adds to its value as a synthon by providing a reliable and predictable means of achieving the ubiquitous head to tail connectivity of isoprene units.