TY - JOUR
T1 - “Tert‐amino effect” in heterocyclic synthesis. Synthesis of thieno[3,2‐e]indolizines and thieno[2,3‐c]quinolizines
AU - Verboom, W.
AU - Verboom, C.
AU - Eissink, I.M.
AU - Lammerink, B.H.M.
AU - Reinhoudt, D.N.
PY - 1990
Y1 - 1990
N2 - A new and convenient route for the synthesis of the thieno[3,2‐e]indolizines 4a,b,d, the thieno[2,3‐c]quinolizine 4e and their [1]benzothieno analogues 9a,b is presented. Reaction of the (dialkylamino)thiophenes 1, 5 and 7 with (methoxymethylene)malononitrile (2) gives the Michael adducts 3, 6 and 8. Heating of 3 and 8 in refluxing 1‐butanol gives the cyclized products 4 and 9. This cyclization proceeds via a 1,5 hydrogen shift, followed by an intramolecular addition of the carbanion to the iminium double bond in the intermediate 10 formed. The scope and limitations of this approach are discussed.
AB - A new and convenient route for the synthesis of the thieno[3,2‐e]indolizines 4a,b,d, the thieno[2,3‐c]quinolizine 4e and their [1]benzothieno analogues 9a,b is presented. Reaction of the (dialkylamino)thiophenes 1, 5 and 7 with (methoxymethylene)malononitrile (2) gives the Michael adducts 3, 6 and 8. Heating of 3 and 8 in refluxing 1‐butanol gives the cyclized products 4 and 9. This cyclization proceeds via a 1,5 hydrogen shift, followed by an intramolecular addition of the carbanion to the iminium double bond in the intermediate 10 formed. The scope and limitations of this approach are discussed.
U2 - 10.1002/recl.19901090907
DO - 10.1002/recl.19901090907
M3 - Article
AN - SCOPUS:84987143438
SN - 0165-0513
VL - 109
SP - 481
EP - 484
JO - Recueil des Travaux Chimiques des Pays‐Bas
JF - Recueil des Travaux Chimiques des Pays‐Bas
IS - 9
ER -