Ultrasound-promoted formation of isopentenyl alcohol dianion: straightforward synthesis of perhydrofuro (2,3-b)furans

Ultrasound has been found to accelerate the formation of isopentenyl alcohol dianion by metalation with butyllithium in diethyl ether-tetrahydrofuran. The reaction of this dianion with carbonyl compounds followed by intramolecular acetalization under Wacker-type conditions provides a direct route for the synthesis of 2-substituted perhydrofuro[2,3-b]furans.Spanish Ministerio de Educación y Ciencia (MEC; grant no. CTQ2007-65218 and Consolider Ingenio 2010-CSD2007-00006) and the Generalitat Valenciana (grant no. PROMETEO/2009/039)