Patent IL-80258-A0 (IL)
Title: Pyrane derivatives and their preparation
IPC: C07D317/00
Filed: 1986-10-08
Abstract: For the Contracting States BE, CH, LI, DE, FR, GB, IT 1. A pyran derivative of the formula la or lb  see diagramm : EP0219091,P15,F1 where R**1 is C1 -C18 -alkyl or phenyl which is unsubstituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, R**2, R**3 and R**4 are each hydrogen, C1 -C6 -alkyl or phenyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, and A is a radical CH2-OR**5, where R**5 is C1 -C4 -alkyl or C2 -C8 -alkoxyalkyl or is bensyl which is unsubstituted substituted in the phenyl ring by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, or is tetrahydropyran-2yl, C1 -C4 -trialkylsilyl, formyl, C2 -C4 -alkylcarbonyl or benzoyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, or A is a radical CH(OR**6)2 , where R**6 is C1 -C4 -alkyl or C1 -C4 -alkyl or C1 -C4 -alkyl-carbonyl, or a radical CH(OR**6)2 which is unsubstituted or C1 -C4 -alkyl-substituted 1,3-dioxan-2-yl or unsubstituted or C1-C4-alkyl-substituted 1,3-dioxolan-2-yl, or A is a radical CO-OR**7, where R**7 is C1 -C4 -alkyl or phenyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, with the proviso that R**4 is not C1 -C4 -alkyl or unsubstituted or substituted phenyl when A is the radical CO-OR**7. For the Contracting State : AT 1. A process for the preparation of a pyran derivative of the formula la or lb  see diagramm : EP0219091,P16,F1  where R**1 is C1 -C18 -alkyl or phenyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, R**2, R**3 and R**4 are each hydrogen, C1 -C6 -alkyl or phenyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, and A is a radical CH2-OR**5, where R**5 is C1 -C4 -alkyl or C2 -C8 -alkoxyalkyl or is benzyl which is unsubstituted or substituted in the phenyl ring by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, or is tetrahydropyran-2yl, C1-C4-trialkylsilyl, formyl, C2 -C4 -alkylcarbonyl or benzyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, or A is a radical CH(OR**6)2 , where R**6 is C1 -C4 -alkyl or C1 -C4 -alkyl or C1 -C4 -alkyl-carbonyl, or a radical CH(OR**6)2  which is unsubstituted or C1 -C4 -alkyl-substituted 1,3-dioxan-2-yl or unsubstituted or C1 -C4 -alkyl-substituted 1,3-dioxolan-2-yl, or A is a radical CO-OR**7, where R**7 is C1 -C4 -alkyl or phenyl which is unsubstituted or substituted by C1 -C4 -alkyl, C1 -C4 -alkoxy or halogen, with the proviso that R**4 is not C1 -C4 -alkyl or unsubstituted or substituted phenyl when A is the radical CO-OR**7, wherein an unsaturated carbonyl compound of the formula ll  see diagramm : EP0219091,P16,F2  is reacted with a enol ether of the formula lll see diagramm : EP0219091,P17,F3  at from 100 to 3008C under from 1 to 1000 bar in the presence or absence of an inert solvent and of an inert protective gas, and, if desired, the resulting dihydropyran derivative of the formula la is converted to a tetrahydropyran derivative of the formula lb by means of hydrogen at from -20 to +3008C and under from 1 to 300 bar in the presence of a hydrogenation catalyst.