Introduction 5-Monosubstituted isopropylidene malonates arc important synthetic organic intermediates. Since isopropylidene malonate has a stronger acidity （pK;=4.57）, its direct alkylation with alkyl halides usuall...Introduction 5-Monosubstituted isopropylidene malonates arc important synthetic organic intermediates. Since isopropylidene malonate has a stronger acidity （pK;=4.57）, its direct alkylation with alkyl halides usually gives 5,5-disubstitutcd isopropylidene malonates.展开更多
Aim To optimize the reaction condition for preparation of 3-spiro-1, 3, 4-oxadiazole substituted fructose and hydrolysis of its isopropylidenes stepwisely. Methods Cyclohexane was added to the reaction mixture every 8...Aim To optimize the reaction condition for preparation of 3-spiro-1, 3, 4-oxadiazole substituted fructose and hydrolysis of its isopropylidenes stepwisely. Methods Cyclohexane was added to the reaction mixture every 8 h to remove acetic acid at 90 ℃. The isopropylidenes were hydrolyzed in 80% AcOH at 60 ℃ stepwisely in a reaction time- dependent manner. Results The yields of cyclization products 1b and 1c were improved from 53% and 51% to 74% and 79% respectively. The 1, 2-di-O-isopropylidene product 3 was obtained after 1 h and the total deprotected product 4 was obtained after 3 h in 80% AcOH at 60 ℃. Conclusion The yield of 1 is improved by cyclohexane-aided azeotropic removal of AcOH from the reaction mixture. Deprotection of 1 in 80% AcOH at 60 ℃ gives 3 or 4 after different time periods.展开更多
Treatment of 11-isopropylidene-anti-4, 5-epoxy-endo-tricyclo[6. 2. 1. 02.7] undeca-4, 9-diene-3,6-dione(6) with methanolic sodium hydroxide results in Favorskii-type ring contraction with concomitant Cope rearrangemen...Treatment of 11-isopropylidene-anti-4, 5-epoxy-endo-tricyclo[6. 2. 1. 02.7] undeca-4, 9-diene-3,6-dione(6) with methanolic sodium hydroxide results in Favorskii-type ring contraction with concomitant Cope rearrangement and Haller-Bauer cleavage, thereby affording dimethyl9-isopropxlidene-cis-bicyclo[4. 3. 0 ] nonane-(2S)-2, 3-dicarboxylate(7) as the ultimate product. The structure of 7 was confirmed by single crystal X-ray analysis展开更多
The condensation of aromatic aldehydes with isopropylidene malonate or 5,5-dimethyl-1,3-cyclohexanedione is carried out by DMF as solvent without catalyst.
以α D 葡萄糖为原料,经异丙叉基保护、异丙叉基选择性水解反应合成1,2 氧 异丙叉基 α D 葡萄糖。研究了影响异丙叉基选择性水解反应的主要因素,用核磁共振、红外光谱与薄层色谱等分析手段对水解产物进行了结构鉴定。两步反应总收率为...以α D 葡萄糖为原料,经异丙叉基保护、异丙叉基选择性水解反应合成1,2 氧 异丙叉基 α D 葡萄糖。研究了影响异丙叉基选择性水解反应的主要因素,用核磁共振、红外光谱与薄层色谱等分析手段对水解产物进行了结构鉴定。两步反应总收率为45%。该合成方法简便,原料易得,具有较大的应用潜力。展开更多
The solid condensation of isopropylidene malonate with aromatic aldehydes were carried out by grinding at room temperature or heating at 110～120 ℃ to give 5 arylidene 2,2 dimethyl 1,3 dioxane 4,6 dione . Both condit...The solid condensation of isopropylidene malonate with aromatic aldehydes were carried out by grinding at room temperature or heating at 110～120 ℃ to give 5 arylidene 2,2 dimethyl 1,3 dioxane 4,6 dione . Both conditions afford the condensation high reaction activity. The yield of the product under grinding for 20 min followed by standing for 48 h at room temperature is 56%～80% and that by heating at 110～120 ℃ for 12 min is 55%～74%, respectively.展开更多
基金Supported by the National Natural Science Foundation of Chinathe Basic Research Foundation of Zhejian Educational Commission.
文摘Introduction 5-Monosubstituted isopropylidene malonates arc important synthetic organic intermediates. Since isopropylidene malonate has a stronger acidity （pK;=4.57）, its direct alkylation with alkyl halides usually gives 5,5-disubstitutcd isopropylidene malonates.
文摘Aim To optimize the reaction condition for preparation of 3-spiro-1, 3, 4-oxadiazole substituted fructose and hydrolysis of its isopropylidenes stepwisely. Methods Cyclohexane was added to the reaction mixture every 8 h to remove acetic acid at 90 ℃. The isopropylidenes were hydrolyzed in 80% AcOH at 60 ℃ stepwisely in a reaction time- dependent manner. Results The yields of cyclization products 1b and 1c were improved from 53% and 51% to 74% and 79% respectively. The 1, 2-di-O-isopropylidene product 3 was obtained after 1 h and the total deprotected product 4 was obtained after 3 h in 80% AcOH at 60 ℃. Conclusion The yield of 1 is improved by cyclohexane-aided azeotropic removal of AcOH from the reaction mixture. Deprotection of 1 in 80% AcOH at 60 ℃ gives 3 or 4 after different time periods.
文摘Treatment of 11-isopropylidene-anti-4, 5-epoxy-endo-tricyclo[6. 2. 1. 02.7] undeca-4, 9-diene-3,6-dione(6) with methanolic sodium hydroxide results in Favorskii-type ring contraction with concomitant Cope rearrangement and Haller-Bauer cleavage, thereby affording dimethyl9-isopropxlidene-cis-bicyclo[4. 3. 0 ] nonane-(2S)-2, 3-dicarboxylate(7) as the ultimate product. The structure of 7 was confirmed by single crystal X-ray analysis
文摘The condensation of aromatic aldehydes with isopropylidene malonate or 5,5-dimethyl-1,3-cyclohexanedione is carried out by DMF as solvent without catalyst.
文摘The solid condensation of isopropylidene malonate with aromatic aldehydes were carried out by grinding at room temperature or heating at 110～120 ℃ to give 5 arylidene 2,2 dimethyl 1,3 dioxane 4,6 dione . Both conditions afford the condensation high reaction activity. The yield of the product under grinding for 20 min followed by standing for 48 h at room temperature is 56%～80% and that by heating at 110～120 ℃ for 12 min is 55%～74%, respectively.
