5-(hydroxymethylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 5-(hydroxymethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (8.6 g, 50 mmole), described by Bihlmayer et al., supra, and mercaptoacetic acid methyl ester (13 g, 0.125 mole) in dry methanol (50 mL) was heated at reflux for 2 hr. Thereafter, the mixture was stirred for 18 hr at 20°-22° C., and then poured into ice-water. The resultant mixture was extracted with diethyl ether. The extract was dried (MgSO4) and concentrated to dryness under reduced pressure. The residue (8.0 g) was purified by chromatography on silica gel, using 30% ethyl acetate in hexane (v/v) as the eluant. The pure fractions were combined and the solvent removed under reduced pressure. Crystallization of the residue from ethyl acetate-hexane gave the title compound; mp 117°-118° C.; NMR (CDCl3) δ 1.7 (s, 6H), 3.65 (s, 2H), 3.75 (s, 3H), 8.95 (s, 1H); IR (CHCl3) 1735, 1700, 1535 cm-1 ; UVλmax (MeOH) 315 um (ε 8900), 260 (7950). was heated at reflux for 2 hr The resultant mixture was extracted with diethyl ether The extract was dried (MgSO4) concentrated to dryness under reduced pressure The residue (8.0 g) was purified by chromatography on silica gel the solvent removed under reduced pressure Crystallization of the residue from ethyl acetate-hexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 5-(hydroxymethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (8.6 g, 50 mmole), described by Bihlmayer et al., supra, and mercaptoacetic acid methyl ester (13 g, 0.125 mole) in dry methanol (50 mL) was heated at reflux for 2 hr. Thereafter, the mixture was stirred for 18 hr at 20°-22° C., and then poured into ice-water. The resultant mixture was extracted with diethyl ether. The extract was dried (MgSO4) and concentrated to dryness under reduced pressure. The residue (8.0 g) was purified by chromatography on silica gel, using 30% ethyl acetate in hexane (v/v) as the eluant. The pure fractions were combined and the solvent removed under reduced pressure. Crystallization of the residue from ethyl acetate-hexane gave the title compound; mp 117°-118° C.; NMR (CDCl3) δ 1.7 (s, 6H), 3.65 (s, 2H), 3.75 (s, 3H), 8.95 (s, 1H); IR (CHCl3) 1735, 1700, 1535 cm-1 ; UVλmax (MeOH) 315 um (ε 8900), 260 (7950). was heated at reflux for 2 hr The resultant mixture was extracted with diethyl ether The extract was dried (MgSO4) concentrated to dryness under reduced pressure The residue (8.0 g) was purified by chromatography on silica gel the solvent removed under reduced pressure Crystallization of the residue from ethyl acetate-hexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Next, this methoxy methylene Meldrum's acid (25 g, 0.13 mol) was dissolved in chloroform (200 ml), followed by adding 2N-HCl (50 ml), agitating the mixture at room temperature, allowing it to still standing, separating the chloroform layer, saturating the aqueous layer with sodium chloride, extracting the solution with chloroform, combining the extract solution with the previously obtained chloroform solution, drying over anhydrous magnesium sulfate, filtering off the drying agent, and distilling off chloroform under reduced pressure to obtain raw formyl Meldrum's acid as residue, adding ether thereto, filtering off, further washing with ether, vaporizing the remaining ether and recrystallizing the resulting crystals from a mixed solvent of dichloromethanehexane to obtain formyl Meldrum's acid in the form of colorless crystals (20.5 g, yield 89%) having a m.p. of 95°-96° C. separating the chloroform layer saturating the aqueous layer with sodium chloride extracting the solution with chloroform drying over anhydrous magnesium sulfate filtering off the drying agent distilling off chloroform under reduced pressure to obtain raw formyl Meldrum's acid as residue filtering off further washing with ether recrystallizing the resulting crystals from a mixed solvent of dichloromethanehexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Acetone (2.9 g) was added to sufficiently dehydrated toluene (500 ml) and the mixture was heated under reflux in a reaction flask equipped with a reflux condenser. While the reflux was continued, a warm solution obtained by dissolving formyl Meldrum's acid (8.6 g) in toluene (500 ml) on heating was dropwise added over about 2 hours, followed by subjecting the reaction mixture to heating under reflux for additional one hour and then subjecting the resulting reaction mixture to purifying operation in the same manner as in Example 1 to obtain 2,2-dimethyl-1,3-dioxin-4-one (5.3 g, yield 82%). the mixture was heated under reflux in a reaction flask equipped with a reflux condenser a warm solution obtained on heating was dropwise added over about 2 hours to heating under reflux for additional one hour the resulting reaction mixture to purifying operation in the same manner as in Example 1

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Although the reaction mechanism is unknown, a process may be considered that at an intermediate step of the reaction, carbon dioxide, acetone and formyl ketene as intermediates are formed from formyl Meldrum's acid, and the formyl ketene reacts with the carbonyl compound to give the objective 1,3-dioxin-4-one derivative. In such a process, since the intermediate formyl ketene is extremely reactive, it is considered that resin formation is promoted in the case of high concentration reaction.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The derivatives have not heretofore been known at all, but for the first time the present inventors have found a process for producing 2,2-dimethyl-1,3-dioxin-4-one as a compound belonging thereto. Namely, according to the process reported by the present inventors in Chem. Pharm. Bull. 31, (6) 1896 (1983), 2,2-dimethyl-1,3-dioxin-4-one was obtained from formyl Meldrum's acid in the presence of acetone and using a small amount of toluene or xylene as solvent, with a yield of 31%. This formyl Meldrum's acid seems to have a higher reactivity than that of similar acetyl Meldrum's acid. That is, in the case of the latter acid, its thermal decomposition yielded 2,2,6-trimethyl-1,3-dioxin-4-one, whereas in the case of the former acid, its mere heating in the absence of solvent formed only a resinous substance without yielding 2,2-dimethyl-1,3-dioxin-4-one, but when the former acid was heated in a xylene solvent containing acetone, the compound was obtained for the first time. However, its yield was not only low (yield: 31% as described above), but the loss of the raw material acid due to the resin formation was so great that the recovery of the raw material was impossible.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Next, this methoxy methylene Meldrum's acid (25 g, 0.13 mol) was dissolved in chloroform (200 ml), followed by adding 2N-HCl (50 ml), agitating the mixture at room temperature, allowing it to still standing, separating the chloroform layer, saturating the aqueous layer with sodium chloride, extracting the solution with chloroform, combining the extract solution with the previously obtained chloroform solution, drying over anhydrous magnesium sulfate, filtering off the drying agent, and distilling off chloroform under reduced pressure to obtain raw formyl Meldrum's acid as residue, adding ether thereto, filtering off, further washing with ether, vaporizing the remaining ether and recrystallizing the resulting crystals from a mixed solvent of dichloromethanehexane to obtain formyl Meldrum's acid in the form of colorless crystals (20.5 g, yield 89%) having a m.p. of 95°-96° C. separating the chloroform layer saturating the aqueous layer with sodium chloride extracting the solution with chloroform drying over anhydrous magnesium sulfate filtering off the drying agent distilling off chloroform under reduced pressure to obtain raw formyl Meldrum's acid as residue filtering off further washing with ether recrystallizing the resulting crystals from a mixed solvent of dichloromethanehexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Acetone (2.9 g) was added to sufficiently dehydrated toluene (500 ml) and the mixture was heated under reflux in a reaction flask equipped with a reflux condenser. While the reflux was continued, a warm solution obtained by dissolving formyl Meldrum's acid (8.6 g) in toluene (500 ml) on heating was dropwise added over about 2 hours, followed by subjecting the reaction mixture to heating under reflux for additional one hour and then subjecting the resulting reaction mixture to purifying operation in the same manner as in Example 1 to obtain 2,2-dimethyl-1,3-dioxin-4-one (5.3 g, yield 82%). the mixture was heated under reflux in a reaction flask equipped with a reflux condenser a warm solution obtained on heating was dropwise added over about 2 hours to heating under reflux for additional one hour the resulting reaction mixture to purifying operation in the same manner as in Example 1

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Although the reaction mechanism is unknown, a process may be considered that at an intermediate step of the reaction, carbon dioxide, acetone and formyl ketene as intermediates are formed from formyl Meldrum's acid, and the formyl ketene reacts with the carbonyl compound to give the objective 1,3-dioxin-4-one derivative. In such a process, since the intermediate formyl ketene is extremely reactive, it is considered that resin formation is promoted in the case of high concentration reaction.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The derivatives have not heretofore been known at all, but for the first time the present inventors have found a process for producing 2,2-dimethyl-1,3-dioxin-4-one as a compound belonging thereto. Namely, according to the process reported by the present inventors in Chem. Pharm. Bull. 31, (6) 1896 (1983), 2,2-dimethyl-1,3-dioxin-4-one was obtained from formyl Meldrum's acid in the presence of acetone and using a small amount of toluene or xylene as solvent, with a yield of 31%. This formyl Meldrum's acid seems to have a higher reactivity than that of similar acetyl Meldrum's acid. That is, in the case of the latter acid, its thermal decomposition yielded 2,2,6-trimethyl-1,3-dioxin-4-one, whereas in the case of the former acid, its mere heating in the absence of solvent formed only a resinous substance without yielding 2,2-dimethyl-1,3-dioxin-4-one, but when the former acid was heated in a xylene solvent containing acetone, the compound was obtained for the first time. However, its yield was not only low (yield: 31% as described above), but the loss of the raw material acid due to the resin formation was so great that the recovery of the raw material was impossible.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 5-(hydroxymethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (8.6 g, 50 mmole), described by Bihlmayer et al., supra, and mercaptoacetic acid methyl ester (13 g, 0.125 mole) in dry methanol (50 mL) was heated at reflux for 2 hr. Thereafter, the mixture was stirred for 18 hr at 20°-22° C., and then poured into ice-water. The resultant mixture was extracted with diethyl ether. The extract was dried (MgSO4) and concentrated to dryness under reduced pressure. The residue (8.0 g) was purified by chromatography on silica gel, using 30% ethyl acetate in hexane (v/v) as the eluant. The pure fractions were combined and the solvent removed under reduced pressure. Crystallization of the residue from ethyl acetate-hexane gave the title compound; mp 117°-118° C.; NMR (CDCl3) δ 1.7 (s, 6H), 3.65 (s, 2H), 3.75 (s, 3H), 8.95 (s, 1H); IR (CHCl3) 1735, 1700, 1535 cm-1 ; UVλmax (MeOH) 315 um (ε 8900), 260 (7950). was heated at reflux for 2 hr The resultant mixture was extracted with diethyl ether The extract was dried (MgSO4) concentrated to dryness under reduced pressure The residue (8.0 g) was purified by chromatography on silica gel the solvent removed under reduced pressure Crystallization of the residue from ethyl acetate-hexane

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Next, this methoxy methylene Meldrum's acid (25 g, 0.13 mol) was dissolved in chloroform (200 ml), followed by adding 2N-HCl (50 ml), agitating the mixture at room temperature, allowing it to still standing, separating the chloroform layer, saturating the aqueous layer with sodium chloride, extracting the solution with chloroform, combining the extract solution with the previously obtained chloroform solution, drying over anhydrous magnesium sulfate, filtering off the drying agent, and distilling off chloroform under reduced pressure to obtain raw formyl Meldrum's acid as residue, adding ether thereto, filtering off, further washing with ether, vaporizing the remaining ether and recrystallizing the resulting crystals from a mixed solvent of dichloromethanehexane to obtain formyl Meldrum's acid in the form of colorless crystals (20.5 g, yield 89%) having a m.p. of 95°-96° C. separating the chloroform layer saturating the aqueous layer with sodium chloride extracting the solution with chloroform drying over anhydrous magnesium sulfate filtering off the drying agent distilling off chloroform under reduced pressure to obtain raw formyl Meldrum's acid as residue filtering off further washing with ether recrystallizing the resulting crystals from a mixed solvent of dichloromethanehexane