412324-05-1Relevant articles and documents
Thermally induced cyclobutenone rearrangements and domino reactions
Harrowven, David C.,Pascoe, David D.,Guy, Ian L.
, p. 425 - 428 (2008/02/02)
(Chemical Equation Presented) Four thermal-rearrangement pathways and a domino reaction leading to quinones arise from the thermolysis of cyclobutenones. The course of vinylcyclobutenone rearrangements is dictated by the nature of the substituent, R (see
Stereocontrolled synthesis of 6-s-cis- and 6-s-trans-locked 9Z-retinoids by hydroxyl-accelerated Stille coupling of (Z)-tri-n-butylstannylbut-2-en-1-ol and bicyclic dienyl triflates
Dominguez, Beatriz,Pazos, Yolanda,De Lera, Angel R.
, p. 5917 - 5925 (2007/10/03)
Analogues of 9-cis-retinoic acid with locked 6-s-cis and 6-s-trans conformations have been stereoselectively synthesized using a Stille coupling reaction between bicyclic dienyl triflates (5 and 6, respectively) and (Z)-tributylstannylbut-2-en-1-ol (7) to stablish the Z geometry of the polyenic side chain. The mild conditions (25 °C, 30 min) of this coupling stand in contrast to the reluctance of the isomeric (E)-tributylstannylbut-2-en-1-ol (18) to react with triflates 5/6. The significant rate differences experimentally observed in Stille reactions between isomeric (Z)- and (E)-tri-n-butylstannylalkenols in favor of the former isomer, even with highly hindered alkenyl triflates, is ascribed to internal coordination of palladium to the heteroatom in the presumably rate-limiting transmetalation step. Dienals and trienals with an E geometry, which are not efficiently available by direct coupling of the corresponding triflates and E-stannanes, can in turn be obtained by isomerization of their Z-isomers.
