Synthesis of 5-propynyloxycycloalkanepyrimidines and their selectivity and reactivity in intramolecular Diels-Alder reactions.
作者:Werner A.W. Stolle、Jacqueline M. Veurink、Antonius T.M. Marcelis、Henk C. van der Plas
DOI:10.1016/s0040-4020(01)88723-8
日期:1992.2
The 5-propynyloxycycloalkane pyrimidines IIIA (17 - 20), IIIB (21 - 24), and IIIC (25, 26) and the 5-(1-propynyloxyethyl)pyrimidines IIID (27, 28), easily undergo intramolecular Diels-Alder reactions with inverse electron demand and a subsequent retro Diels-Alder reaction in which R1CN (R1 = H, Me) or X-CH2CN (X = -CH2, -CH2CH2, -H) is expelled. For the compounds IIIA and IIIB the extrusion of X-CH2CN is favoured, yielding 3-(3-cyanopropyl)-1,3-dihydro-6-phenyl-R1-R2-furo[3,4-c]pyridines (29 - 36). The compounds 17 and 21 also yielded 4-phenyl-2H-6,7,8,8a-tetrahydro-furo[4,3,2-de]quinoline (38), by expulsion of HCN or MeCN respectively, which constitute a new class of heterocyclic compounds. For the compounds IIIC and IIID the extrusion of HCN is favoured as compared to the extrusion of X-CH2CN. In case of IIIC this also gives a hitherto unknown class of heterocyclic ring systems namely 2H-1,6,7,8,9,9a-hexahydro-4-phenyl-9a-R1-5-aza-1-oxo-benz[c,d]azulenes (39, 40). The reactivity of the compounds III towards the cycloaddition appears to be strongly influenced by the nature of the substituent R2 if R1 = H. However, if R1 = Me the effect of R2 on the reactivity was very small. The ratio of the products V and VI appears to depend mainly on the nature of -X-.