Patent GB-1427541-A (GB)
Title: Cyclopenteno-b-furan derivatives
IPC: C07C45/29
Filed: 1973-01-15
Abstract: 1427541 Cyclopenta[b]furanones IMPERIAL CHEMICAL INDUSTRIES Ltd 21 Dec 1973 [15 Jan 1973] 2032/73 Heading C2C Novel cyclopenta[b]furanones of the Formula I and absolute stereochemistry wherein R<SP>1</SP> is C 4-10  alkyl, C 4-10  alkenyl, a radical of the formula -A<SP>1</SP>-OR<SP>2</SP>, wherein A<SP>1</SP> is C 1-9  alkylene, and R<SP>2</SP> is C 1-9  alkyl or C 5-7  cycloalkyl, provided A<SP>1</SP> and R<SP>2</SP> together contain not more than 10 C atoms; a radical of the formula -A<SP>2</SP>R<SP>3</SP>, wherein A<SP>2</SP> is a direct bond or C 1-3  alkylene, and R<SP>3</SP> is aryl optionally substituted by halogen, NO 2 , C 1-3  alkyl, C 1-3  haloalkyl, C 1-3  alkoxy or di(C 1-3  alkyl)-amino; a radical of the formula -A<SP>3</SP>.A<SP>4</SP>.R<SP>4</SP>, wherein A<SP>3</SP> is C 1-3  alkylene optionally substituted by 1 or 2 C 1-3  alkyl radicals, A<SP>4</SP> is O, S, SO or C 1-4  alkylimino, and R<SP>4</SP> is aryl, benzyl or furfuryl optionally substituted by OH, NO 2 , phenyl, halogen, C 1-4  alkyl, C 2-4  alkenyl, C 1-4  haloalkyl, C 1-4  alkoxy, C 2-4  alkenyloxy, C 1-4  acylamino or di- (1-3 alkyl)amino; or a radical of the formula -A<SP>3</SP>.A<SP>5</SP>.R<SP>5</SP>, wherein A<SP>5</SP> is O, S, SO, SO 2 , NH, C 1-4  alkylimino or a direct bond, or A<SP>3</SP> and A<SP>5</SP> together are a direct bond, and R<SP>5</SP> is an aromatic heterocyclic radical of one or two 5- or 6- membered rings, containing in one ring only, 1 or 2 non-adjacent hetero-atoms, and optionally bearing 1 to 3 alkyl radicals or halogen atoms as substituents, are prepared by oxidizing optically active hydroxy-enols of the Formula II obtained by hydrolysing the corresponding 5α- (p-phenylbenzoyloxy) - 4# - (3 - R<SP>1</SP> - 3 - hydroxytrans - 1 - propenyl) - 3,3a#.4.5.6,6a# - hexahydro - 2H - cyclopenta[b]furan - 2 - ones, which are prepared by reducing the corresponding 5x - (p - phenylbenzoyloxy) - 4# - (3 - R<SP>1</SP> - 3- oxo - trans - 1 - propenyl) - 3,3a#,4.5.6,6a#- hexahydro - 2H - cyclopenta[b]furan - 2 - ones, resulting from the reaction of phosphonates of the formula (CH 3 O) 2 PO.CH 2 COR<SP>1</SP> in the presence of strong bases with 5α-(p-phenylbenzoyloxy) - 3,3a#,4.5.6,6a# - hexahydro - 2H - cyclopenta[b]furan - 4# - carbaldehyde, obtained hydrolysing 5α - (p - phenylbenzoyloxy) - 3,3a#,- 4.5.6,6a# - hexahydro - 4# - dimethoxymethyl- 2H - cyclopenta[b]furan - 2 - one, which is prepared by deiodinating 5α-(p-phenylbenzoyloxy)- 6 - iodo - 3,3a#,4.5.6,6a,# - hexahydro - 4#- dimethoxymethyl - 2H - cyclopenta[b]furan - 2- one, obtained by acylating 5α-hydroxy-6-iodo- 3,3a#,4.5.6,6a# - hexahydro - 4# - dimethoxymethyl - 2H - cyclopenta[b]furan-2-one, resulting from the Bayer-Villiger oxidation and rearrangement with potassium tri-iodide of (-)-7- dimethoxymethylbicyclo[2,2,1]hept- 5 - en - 2 - one, which is prepared by oxidizing (-)-7-dimethoxymethylbicyclo[2,2,1]hept- 5 - en - 2 - endo - ol, resulting from the hydrolysis of the corresponding optically active hemi-phthalate, obtained by resolution of the amphetamine salt and hydrolysis of the resolved salt. (Œ) - 7 - Dimethoxymethylbicyclo[2,2,1]- hept - 5 - en - 2 - endo - ol is obtained by reducing (Œ) - 7 - dimethoxymethylbicyclo- [2,2,1]hept-5-en-2-one.