Glycerol is applied as a green, biodegradable and reusable promoting medium for one-pot three component synthesis of 4H-pyrans under catalyst-free conditions. A broad range of substrates including aromatic and heteroaromatic aldehydes, isatine derivatives, acenaphthenequinone and ninehydrine are condensed with carbonyl compounds possessing a reactive α-methylene group and alkylmalonates. All reactions are completed in short times, and the products are obtained in good to excellent yields. The reaction medium could be recycled and reused several times without any loss of efficiency.
Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a highly efficient, heterogeneous and recyclable silica-supported ionic liquid catalyst for the synthesis of benzo[b]pyran, bis(benzo[b]pyran) and spiro-pyran derivatives
The reaction of 3-chloropropyl silica (SilprCl) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dry acetone affords silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a new silica-supported ionicliquid catalyst. Afterward, (SB-DBU)Cl is used for the efficientsynthesis of 4H-benzo[b]pyran derivatives via the one-pot, three-componentreaction of carbonyl compounds (cyclohexane-1
3-氯丙基二氧化硅(SilprCl)与1,8-二氮杂双环[5.4.0]十一碳-7-烯(DBU)在干燥的丙酮中的反应得到二氧化硅键合的5-正丙基-八氢-嘧啶基[1,2- a]氯化ze嗪(SB-DBU)Cl作为新型的二氧化硅负载型离子液体催化剂。之后,(SB-DBU)Cl通过羰基化合物(环己烷-1,3-二酮,5,5-一锅法)的三锅法有效合成4 H-苯并[ b ]吡喃衍生物。(1,3-二甲基环己烷-1,3-二酮或3-甲基-1-苯基-2-吡唑啉-5-酮)与芳族醛和烷基丙二酸酯。此外,一些新颖的双(苯并[ b使用(SB-DBU)Cl合成[] pyran] s和在结构上含有羟吲哚和/或喹喔啉部分的多种结构多样的螺-吡喃。将催化剂循环使用十五次,收率不变。