BETA-LACTAM COMPOUNDS AND PRODUCTION PROCESS THEREOF

Abstract: Novel β-lactam compounds of the formula, (wherein OR¹ is a protected or unprotected hydroxyl group; R² is C₁ to C₇ alkyl or aryl; R³ is hydrogen or a tri-substituted silyl, are produced from azetidinone compounds of the formula, (wherein OR¹ is as defined above; X is an electronegative leaving group) are prepared by reaction with (a) stannylallenes of the formula R² CH=C=CH-SnR⁷₃ (wherein R² is as defined above and R⁷ is a C₁-C₄ alkyl or phenyl) or (b) a metal compound of the formula R²-CH(M)C CH (wherein R² is as defined above and M is Mg.halogen, Li, or a titanic or boric acid ester group) to obtain a said β-lactam compound in which R³ is hydrogen". The β-lactam compounds are useful for synthesizing 1β-methylcarbapenem compounds.

Description: This invention relates to novel β-lactam compounds, wich contain a hydroxyethyl group at the 3-position, having the hydroxyl group in the hydroxyethyl group protected or unprotected, and a butynyl group at the 4-position, and also to processes for producing the compounds. Thienamycin ( 1 ) is produced by fungi of Actinomyces and is known to possess extremely potent antimicrobial activities. Its discovery initiated intensive research on carbapenem compounds, resulting in publication of imipenem ( 2 ) in 1981. However, these carbapenem compounds are far from satisfactory in terms of chemical stability and resistance to renal dehydropeptidase-I (DHP-I). Consequently, investigation has been conducted into more stable carbapenem compounds exhibiting potent antimicrobial activity, which led in 1984 to the finding that 1β-methylcarbapenem ( 3 ) having a β-methyl group at the 1-position is stable and possesses strong antimicrobial activity. The said compound ( 3 ) contains four consecutive asymmetric carbons (C₁, C₅, C₆, C₈), and in view of the fact that most of the publications on its synthesis are concerned with the utilization of optically active azetidinone ( 4 ) as an intermediate, the synthesis of the intermediate ( 4 ) has been considered to be the key to the commercial production of the said compound ( 3 ). According to the literature published so far on the synthesis of the compound ( 4 ), four reports dealt with the stereospecific synthesis, one report was concerned with the stereospecific reduction and one report with isomerization, as is illustrated below in the reaction formulae: EP-A-0171064 discloses the preparation of 3-(1-hydroxyethyl)-4-acetoxy-2-azetidinone from a lithium enolate of an alkyl 3-hydroxybutanoate and ethynylaldimine by the following steps: (a) reaction of said enolate and ethynylaldimine to form 3-(1-hydroxyethyl)-4-ethynyl-2-azetidione; (b) reaction of said 3-(1-hydroxyethyl)-4-ethynyl-2-azetidinone with a mercuric compound in the presence of sulphuric acid and/or ammonium sulphate to form 3-(1-hydroxyethyl)-4-acetyl-2-azetidinone; and (c) reaction of said 3-(1-hydroxyethyl)-4-acetyl-2-azetidinone with a peracid in an inert solvent (Bayer-Villeger reaction) to form 3-(1-hydroxyethyl)-4-acetoxy-2-azetidinone. 3-(1-hydroxyethyl)-4-acetoxy-2-azetidinone is a key intermediate in the preparation of Thienamycin and other carbapenem compounds and is converted into said carbapenem compounds in known manner. The hydroxy, ethynyl and ring imine groups can be protected during the reaction steps with trialkylsilyl groups. Shibasaski et al (J.C.S., Chem. Commun. 22 (1982) 1324-1325) disclose the chiral synthesis of (-)-3-[1-(tert.butyldimethylsilyloxy)ethyl]-4-(1-propyn-3-yl)-2-azetidinone using the asymmetric introduction of a phenylthio group to 4-phenylsulphonyl-1-azetidinone as a key step. In particular, said 3-(1-trialkylsilyloxyethyl)-4-propynyl-2-azetidinone is obtained by the following steps: (a) reaction of 4-acetoxy-2-azetidinone with thiophenol to form (4)-4-phenylthio-2-azetidinone; (b) protection of the ring imine group of said (4)-4-phenylthio-2-azetidinone to form (-)-N-(tert.-butyldimethylsilyl)-4-phenylthio-2-azetidinone; (c) Aldol condensation of said N-protected-4-phenylthio-2-azetidinone to form diastereomeric N-(tert.butyldimethylsilyl)-3-(1-hydroxyethyl)-4-phenylthio-2-azetidinone; (d) Oxidation of said N-protected-3-(1-hydroxyethyl)-4-phenylthio-2-azetidione to form (-)-N-(tert.-butyldimethylsilyl)-3-acetoxy-4-phenylthio-2-azetidinone to form (-)-N-(tert.butyldimethylsilyl)-3-acetoxy-4-phenylthio-2-azetidinone; (e) Reduction of said N-protected-3-acetoxy-4-phenylthio-2-azetidinone to form diastereomeric N-(tert.butyldimethylsilyl)-3-(1-hydroxy-ethyl)-4-phenylthio-2-azetidinone and separation of (-) isomer thereof; (f) Deprotection of said (-) N-protected-3-(1-hydroxyethyl)-4-phenylthio-2-azetidinone to form (+)-3-(1-hydroxyethyl)-4-phenylthio-2-azetidinone; g) Protection of hydroxy group of said 3-(1-hydroxyethyl)-4-phenylthio-2-azetidione by forming tert.butyldimethylsilyl ether therefrom; (h) Oxidation of said 3-(1-tert.butyldimethylsilyloxy)-4-phenylthio-2-azetidinone to form (-)-3-(1-tert.butyldimethylsilyloxy)-4-phenylsulphonyl-2-azetidinone; (i) Gridnard reaction of said 3-(1-tert.butyldimethylsilyloxy)-4-phenylsulphonyl-2-azetidinone to form (-)-3[1-(tert.butyldimethylsilyloxy)ethyl]-4-(1-propyn-3-yl)-2-azetidinone. These methods suffer from the defects that an increased number of steps are required; that the starting compounds are not easy to produce; and that the yields are poor. The present inventors found that the β-lactam compounds having a butynyl group at the 4-position which have not been described in the literature are employable as an important intermediate for 1β-methylcarbapenem compounds and discovered simple and convenient methods for producing the above-described β-lactam compounds, which lead to the establishment of this invention. This invention is directed to: (a) a β-lactam compound of the following general formula: wherein OR¹ is a hydroxyl group or R¹ represents a tri-substituted silyl group of the formula: or a carboxylic acid ester group removable by reduction; R² is a C₁ to C₇ alkyl or phenyl group; R³ is hydrogen or a tri-substituted silyl group of the formula: and R⁴, R⁵ and R⁶ each independently represent a C₁ to C₄ alkyl group or phenyl group, and (b) a process for producing a β-lactam compound of the following formula: wherein OR¹, R² and R³ are as defined hereinbefore which comprises reacting an azetidinone compound represented by the following general formula: wherein OR¹ is as defined hereinbefore and X is an electronegative group removable through reaction, with a stannylallene represented by the general formula R²CHßCßCH-SnR⁷₃ (wherein R² is as defined hereinbefore; R⁷ is a C₁ to C₄ alkyl or phenyl group) in the presence of a Lewis acid to give a β-lactam compound of the following general formula: wherein OR¹ and R² are as defined hereinbefore; isomerizing said β-lactam compound by rection with a base and an organosilyl halide represented by the general formula: (wherein R⁴ R⁵ and R⁶ are as defined hereinbefore and Y is a halogen), successively, to produce a β-lactam compound of the following general formula: wherein OR¹, R², R⁴, R⁵ and R⁶ are as defined hereinbefore, optionally followed by subjecting said B-lactam compound (9) to a removal reaction of the tri-substituted silyl group. Examples of the protective group represented by R¹ include the tri-substituted silyl groups represented by R³, especially tert-butyl-dimethylsilyl, tert-butyldiphenylsilyl and triisopropylsilyl groups, and carboxylic acid ester groups, such as p-nitrobenzyloxycarbonyl and p-methoxybenzyloxycarbonyl groups. As the C₁ to C₇ alkyl group represented by R², there may be mentioned, for example, methyl, ethyl and heptyl groups. Desirable specific examples of R³ include trimethylsilyl, triethylsilyl, triisopropylsilyl, tert-butyldimethylsilyl and dimethylphenylsilyl groups. As the C₁ to C₄ alkyl group being represented individually by R⁴, R⁵ and R⁶, there may be mentioned, for example, methyl, ethyl, propyl, isopropyl, butyl and tert-butyl groups. Examples of the C₁ to C₄ alkyl group represented by R⁷ include methyl, ethyl, propyl and butyl groups. The β-lactam compounds ( 5 ) of this invention are novel and can offer the advantages that the compounds have at the 4-position a butynyl group being convertible into various functional groups and also that the compounds can be produced in the form of β-lactam compounds possessing the desired configuration, for example, compounds ( 5 ′) having the same configuration that the one of four consecutive asymmetric carbons possessed by the above-described 1β-methylcarbapenem compounds, when azetidinone compounds having the corresponding configuration are used as a starting compound in the production process according to this invention. The compounds ( 8 ) and ( 9 ) of this invention can be produced by the following procedure: The azetidinone compound ( 6 ) is reacted with stannylallene ( 7 ) to produce the β-lactam compound ( 8 ). This reaction is carried out in a halogenated hydrocarbon solvent, such as methylene chloride, chloroform and 1,2-dichloroethane, and a hydrocarbon solvent, such as n-hexane, benzene and toluene. Preferable is a halogenated hydrocarbon solvent. The reaction is allowed to proceed in the presence of a Lewis acid. Preferred Lewis acids are boron trifluoride ethyl etherate [BF₃ · (C₂H₅)₂O], trimethylsilyl trifluoromethanesulfonate [(CH₃)₃ · Si-OSO₂CF₃] and tert-butyldimethylsilyl trifluoromethanesulfonate ( Si-OSO₂CF₃). Usually, the reaction temperature is preferably in the range of -10°C to 60°C. In this reaction step, for example, when the optically active azetidinone compound ( 6 ′) is used as a starting compound to undergo the reaction in the presence of BF₃ · (C₂H₅)₂O or (CH₃)₃Si-OSO₂CF₃ being utilized as a catalyst and in methylene chloride at room temperature, the β-lactam compound ( 8 ′) can be obtained almost quantitatively in the following ratios of the α- and β-forms in relation to the configuration of its methyl group: In the case of BF₃ · (C₂H₅)₂O being used as a catalyst; α: β = 4: 1 In the case of (CH₃)₃Si-OSO₂CF₃ being utilized as a catalyst; α: β = 1: 1 The compound ( 8 ) can also be obtained by allowing a metal compound represented by the formula (wherein R² is as defined hereinbefore; M is ―Mg · X (X is halogen), Li, or a titanic acid ester or boric acid ester group, in place of stannylallene, to act on the compound ( 6 ). This reaction proceeds without addition of Lewis acid. The β-lactam compound ( 8 ) as produced in the preceding step is reacted with a base and organosilyl halide, successively. As the base, there are preferably employed lithium alkylamides, such as lithium diisopropylamide, and alkyl lithium, such as n-butyllithium-tetramethylethylenediamine, sec-butyllithium and tert-butyllithium. The reaction is carried out in an anhydrous, inactive solvent, such as anhydrous tetrahydrofuran. The resulting reaction product is subsequently reacted with an organosilyl halide represented by the formula (wherein R⁴, R⁵ and R⁶ are the same or different and each represents a C₁ to C₄ alkyl or phenyl group; Y is a halogen) to produce the β-lactam compound ( 9 ). Examples of the organosilyl halide include trimethylchlorosilane, triethylchlorosilane, tripropylchlorosilane, tert-butyldimethylchlorosilane and triphenylchlorosilane. In the course of this reaction, the α-form of the compound ( 8 ) wherein the alkyl or phenyl group represented by R² is involved in the configuration isomerizes to the β-form. When the above-described compound (8′) having the α-form/β-form ratio of 1: 1, being used as a starting compound in this reaction step, is reacted with 3.5 equivalents each of lithium diisopropylamide and trimethylchlorosilane successively in anhydrous tetrahydrofuran at -78°C, for example, the α-form isomerizes to the β-form, resulting the high yield of the compound ( 9 ′) containing the α-form: β-form (1: 13). The compound ( 9 ) obtained thus can be derived to the compound ( 5 ) through a removal reaction for the trisubstituted silyl group. This reaction can be carried out in easy and quantitative manner by allowing silver nitrate and potassium cyanate successively to act on the compound (9) in a water-containing solvent or alternatively by allowing potassium fluoride to act on the compound in aqueous methanol. By the above described procedure, for example, the compound ( 9 ′) mentioned hereinbefore can be converted into the compound ( 8 ″). In the same manner as described above, the compound having a phenyl group instead of the methyl group in the substituent at 4-position of the azetidinone ring of the compound (8″) can be obtained by employing 3-phenyl-1-tributylstannylallene in place of 3-methyl-1-tributyl-stannylallene. The compounds of this invention can be derived to the important intermediate ( 4 ) as described hereinbefore, for example, through the reaction steps being illustrated below by the reaction formulae: In addition, the compounds of this invention can be converted to optically active azetidinones being derivable into 1β-methylcarbapenem compounds other than those as described above. The β-lactam compounds ( 5 ) having a butynyl group at the 4-position as obtained according to this invention can not only be easily derived to the azetidinone compounds ( 4 ), important intermediates for synthesizing for example 1β-methylcarbapenem ( 3 ), but also be produced in shortened steps in improved yields by starting from azetidinone compounds which are easily available or producible. Below described are examples and reference examples to illustrate more specifically this invention. Reference Example 1 3-Methyl-1-tributylstannylallene (CH ₃ -CHßCßCHSnBu ₃ ) 1-Bromo-3-methylallene (9.69 g) is added to 100 ml of anhydrous ether under a stream of nitrogen, followed by cooling to -78°C. n-Butyllithium (10 w/w% n-hexane solution) (46.7 ml) is added to the mixture under stirring over the period of 15 minutes, followed by stirring at the same temperature for 1 hour. After adding anhydrous tetrahydrofuran (20 ml), chlorotributylstannane (23.7 g) is added to the mixture over a period of 10 minutes, and the reaction mixture is allowed to warm up spontaneously to room temperature, followed by stirring at room temperature for 15 minutes. The reaction solution is poured into water, and extraction is performed with ether. The organic layer is washed with water and saturated aqueous sodium hydrochloride solution, successively, and dried over anhydrous magnesium sulfate. The solvent is removed under reduced pressure, and the residue is purified through silica gel column chromatography (n-hexane) to give 17.4 g of the objective compound. IR (CHCl₃): 1930 cm⁻¹ NMR (CDCl₃) δ: 0.7 to 2.0 (27 H,m), 1.65 (3H, dd, J = 4,7 Hz), 4.23 (1H, dq, J = 7,7 Hz), 5.05 (1H, dq, J = 4,7 Hz) Example 1 (3S, 4R)-4-(1-Butyn-3-yl)-3-[(1R)-1-(tert-butyldimetylsilyloxy)ethyl]-2-azetidinone (5‴) (3R, 4R)-4-Acetoxy-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2 azetidinone (653 mg) is added to 20 ml of anhydrous methylene chloride under a stream of nitrogen, followed by cooling with ice. After adding 3-methyl-1-tributylstannylallene (1.56 g), trimethylsilyl trifluoromethanesulfonate (0.35 ml) is added to the mixture, followed by stirring at the same temperature for 15 minutes and then at room temperature for 14 hours. The reaction solution is concentrated under reduced pressure, and the concentrate is admixed with ether. The mixture is washed with phosphoric acid buffer (pH 7) and admixed with saturated aqueous potassium fluoride solution, followed by stirring vigorously for 1 hour. The resulting precipitate is filtered out, and the filtrate is dried over anhydrous magnesium sulfate, followed by removal of the solvent under reduced pressure. The residue is purified through silica gel column chromatography (n-hexane: ether = 1: 1) to give 626 mg of a 1: 1 mixture of (3S, 4R)-4-[1-butyn-3(R)-yl]-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-azetidinone (α-methyl form) and (3S,4R)-4-[1-butyn-3(S)-yl]-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-azetidinone (β-methyl form). IR (CHCl₃): 3420, 3300, 1755 cm⁻¹ NMR (90 MHz) (CDCl₃) δ: 0.08 (6 H, S), 0.88 (9 H, S), 1.24 (6 H, d, J = 6 Hz), 2.12 (1 H, d, J = 2.5 Hz), 2.59 (1/2 H, m, α-isomer), 2.70 (1/2 H, m, β-isomer), 2.84 (1/2, m, α-isomer), 3.00 (1/2 H, m, β-isomer), 3.57 (1/2 H, dd, J = 7.6, 1.8 Hz, α-isomer), 3.67 (1/2 H, dd, J = 6.4, 2.0 Hz, β-isomer), 4.16-4.26 (1 H, m) Exact mass spectrometry: as C₁₅H₂₇NO₂Si-C₄H₉ Calcd.: 224.1108 Found: 224.1108 Example 2 By following the same procedure as described in Example 1, 0.44 ml of boron trifluoride ethyl etherate (47% ether solution) is used in place of trimethylsilyl fluoromethanesulfonate to produce the compound (5‴) (α-methyl form: β-methyl form = 4: 1). Yield of 569 mg. Example 3 (3S, 4R)-4-[1-Butyn-3(S)-yl]-3-[(1R)-1-(tert-butyl-dimethylsilyloxy)ethyl]-2-azetidinone (5‴) Diisopropylamine (0.34 ml) is added to anhydrous tetrahydrofuran (4.4 ml) under a stream of nitrogen, followed by cooling with ice. n-Butyllitithium (10 w/w% n-hexane solution) (1.6 ml) is added to the solution, followed by stirring at the same temperature for 30 minutes. The solution is cooled to -78°C and admixed with a solution in anhydrous tetrahydrofuran (4.4 ml) of the mixture (5‴) (196 mg) of the α-methyl form and β-methyl form as obtained in Example 1, and the mixed solution is warmed up to -30°C over a 1 hour period, then cooled down to -78°C again and admixed with trimethylchlorosilane (0.31 ml). The reaction solution is allowed to warm up to room temperature spontaneously, and admixed with water and ethyl acetate, and the water layer separated is extracted with ethyl acetate. The combined organic layer is washed with water and saturated aqueous sodium chloride solution, successively and dried over anhydrous magnesium sulfate, followed by removal of the solvent under reduced pressure. The resulting residue is purified through silica gel column chromatography (n-hexane: ethyl acetate = 4: 1) to give 164 mg of (3S, 4R)-4-[trimethylsilyl-1-butyn-3-(S)-yl]-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-azetidinone. IR (CHCl₃): 3425, 2160, 1760 NMR (200 MHz) (CDCl₃) δ: 0.07 (3 H, S), 0.08 (3 H, S), 0.13 (9 H, S), 0.88 (9 H, S), 1.23 (6 H, t, J = 7 Hz), 2.66 (1 H, quint, J = 7 Hz), 2.97 (1 H, bs), 3.63 (1 H, dd, J = 2,7 Hz), 4.20 to 4.27 (1 H, m), 6.37 (1 H, bs). Exact mass spectrometry: as C₁₈H₃₅NO₂Si₂-C₄H₉ Calcd.: 296.1499 Found: 296.1492 The substance is dissolved in ethanol (1.4 ml), and the solution is cooled with ice and admixed gradually with a solution of silver nitrate (178 mg) in ethanol-water (1: 3) (1.7 ml). After stirring for 15 minutes, 9M aqueous potassium cyanide solution (0.58 ml) is added to the solution, followed by stirring for 10 minutes and then at room temperature for 1 hour. The reaction solution is admixed with ether (11 ml) and water (11 ml), and the aqueous layer is extracted with ether. The organic layer is washed with water and dried over anhydrous magnesium sulfate, and the solvent is removed under reduced pressure, followed by purification of the residue through silica gel column chromatography (n-hexane: ether = 2: 1) to give 127 mg of the desired compound. IR (CHCl₃): 3420, 3300, 1755 cm⁻¹ NMR (200 MHz) (CDCl₃) δ: 0.07 (3 H, S), 0.08 (3 H, S), 0.88 (9 H, S), 1.24 (3 H, d, J = 6.8 Hz), 1.25 (3 H, d, J = 6.2 Hz), 2.12 (1 H, d, J = 2.4 Hz), 2.70 (1 H, d, of quint, J = 2.4, 6.8 Hz), 2.99 to 3.02 (1 H, m), 3.67 (1H, dd, J = 2, 6.2 Hz), 4.23(1 H, dq, J = 6.2, 4 Hz), 6.00 (1 H, brs). Exact mass spectrometry: as C₁₅H₂₇NO₂Si-C₄H₉ Calcd.: 224.1108 Found: 224.1108 Reference Example 2 3-Phenyl-1-tributylstannylallene 1-Phenyl-2-propyn-1-ol (1.32 g) is converted to mesylate in accordance with the conventional method while using methanesulfonyl chloride and triethylamine. Tributylstannyllithium as produced by acting on bis-tributylstannane (5.8 g) and an equimolar amount of n-butyllithium (10 w/v% n-hexane solution) (6.4 ml) in tetrahydrofuran (10 ml) is added to a solution of cuprous bromide (1.43 g) and lithium bromide (0.87 g) in anhydrous tetrahydrofuran (30 ml) at -60°C to prepare an organic tin reagent (n-Bu₃SnLi), to which a solution of the above-described mesylate in anhydrous tetrahydrofuran (5 ml) is added at -60°C, followed by stirring for 2 hours. The reaction solution is poured into saturated aqueous ammonium chloride solution, and extraction is performed with ether. The ether layer is dried over anhydrous magnesium sulfate, and the solvent is removed under reduced pressure. The resulting residue is purified by column chromatography on 6% aqueous alumina (n-hexane) to give 2.8 g of the objective compound. IR (CHCl₃): 1920, 1595 cm⁻¹ NMR (90 MHz) (CDCl₃) δ: 0.7 to 1.8 (27 H, m), 5.64 (1 H, d, J = 7 Hz), 5.82 (1H, d, J = 7 Hz), 7.32 to 7.56 (5 H, m). Example 4 (3S, 4R)-4-(3-Phenyl-1-propyn-3-yl)-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-azetidinone By following the same procedure as described in Example 2 except that 3-phenyl-1-tributylstannylallene (1.84 g) is used in place of 3-methyl-1-tributylstannylallene, there is obtained the objective compound. Yield of 640 mg. IR (CHCl₃): 3425, 3320, 1765 cm⁻¹ NMR (500 MHz) (CDCl₃) δ: 0.04 (6 H, S), 0.75 (12/7 H, d, J = 6.7 Hz), 0.86 (9 H, S), 1.04 (16/7 H, d, J = 6.7 Hz), 2.35(1 H, t, J = 2.4 Hz, 2.99 to 3.03 (1 H, m), 3.77 (4/7 H, t, J = 1.8 Hz), 3.78 (3/7 H, t, J = 2.4 Hz), 3.84 (4/7 H, dd, J = 6.7, 2.2 Hz), 3.90 (3/7 H, dd, J = 7.9, 2.2 Hz), 4.11 (4/7 H, dq, J = 4.3, 6.7 Hz), 4.22 (3/7 H, dq, J = 3.1, 6.7 Hz), 7.34 to 7.41 (5 H, m) Example 5 (3S, 4R) -4-(3-Phenyl-1-trimethylsilyl-1-propyn-3 (R)-yl]-3-[(1R) -1-(tert-butyldimethylsilyloxy) ethyl]-2-azetidinone By following the first half of the same procedure as described in Example 3 except that 240 mg of the product as obtained in Example 4 is employed, with lithium diisopropylamide being used as a base, the isomerization reaction through silylation is carried out to produce 102 mg of the objective compound. IR (CHCl₃): 3410, 2180, 1760 cm⁻¹ NMR (90 MHz) (CDCl₃) δ: 0.04 (6 H,S), 0.13 (9 H, S), 0.88 (3 H, d, J = 6 Hz), 0.91 (9 H, S), 3.00 to 3.10 (1 H, m), 3.80 to 3.90 (2 H, m), 4.10 to 4.34 (1 H, m), 7.36 (5 H, S). Example 6 (3S, 4R)-4-(3-Phenyl-1-propyn-3(R)-yl]-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-azetidinone By following the last half of the same procedure as described in Example 3, 100 mg of the product as obtained in Example 5 is subjected to a removal reaction for silylgroup to give 44 mg of the objective compound. IR (CHCl₃): 3425, 8320, 1765 cm⁻¹ NMR (500 MHz) (CDCl₃) δ: 0.04 (6 H, S), 0.75 (3 H, d, J = 6.7 Hz), 0.86 (9 H, S), 2.35 (1 H, d, J = 2.4 Hz), 2.99 to 3.03 (1 H, m), 3.78 (1 H, t, J = 2.4 Hz), 3.90 (1 H, dd, J = 7.9, 2.2 Hz), 4.22(1 H, dq, J = 3.1, 6.7 Hz), 7.34 to 7.40 (5 H, m). Example 7 (3S, 4R)-4-[1-Buten-3(S)-yl]-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]-2-azetidinone The β-lactam compound (5″″) (81 mg) as produced in in Example 3 is dissolved in methanol (1 ml), and 5% Pd-BaSO₄ (1.6 mg) and quinoline (1.6 mg) are added to die solution, which is then allowed to absorb about 6.5 ml of hydrogen under atmospheric pressure at ambient temperature. The reaction solution is filtered, and the filtrate is admixed with ether and water to extract the aqueous layer with ether. The organic layer is washed with water and dried over anhydrous magnesium sulfate. The solvent is removed under reduced pressure, and the residue is purified through silica gel column chromatography (n-hexane: ether = 2: 1) to give 73.4 mg of the objective compound. IR (CHCl₃): 3410, 1750 cm⁻¹ NMR (200 MHz) (CDCl₃) δ: 0.07 (6 H, S), 0.88 (9 H, S), 1.07 (3 H, d, J = 7 Hz) · 1.17 (3 H, d, J = 6 Hz), 2.33 (1 H, brq, J = 7 Hz), 2.82 (1 H, ddd, J = 4.5, 2.5, 1 Hz), 3.52 (1 H, dd, J = 8, 2.5 Hz) 4.18 (1 H, dq, J = 6, 4.5 Hz), 4.96 to 5.22 (2 H, m), 5.60 to 6.00 (2 H, m). Exact mass spectrometry: as C₁₁H₂₀NO₂Si-C₄H₉ Calcd.: 226.126 Found: 226.128

Claims: 1. A β-lactam compound of the following general formula: wherein OR¹ is a hydroxyl group or R¹ represents a tri-substituted silyl group of the formula: or a carboxylic acid ester group removable by reduction; R² is a C₁ to C₇ alkyl or phenyl group; R³ is hydrogen or a tri-substituted silyl group of the formula: and R⁴, R⁵ and R⁶ each independently represent a C₁ to C₄ alkyl group or phenyl group. 2. A compound as claimed in Claim 1, wherein R¹ is a said tri-substituted silyl group or a carboxylic acid ester group removable by reduction and R³ is a said tri-substituted silyl group. 3. A compound as claimed in Claim 1, wherein R¹ is a said tri-substituted silyl group; R² is methyl; and R³ is hydrogen. 4. A compound as claimed in Claim 1, wherein R¹ is tert-butyldimethylsilyl and R³ is hydrogen. 5. A compound as claimed in any one of the preceding claims, wherein said compound has a configuration represented by the following formula: wherein OR¹, R² and R³ are as defined in the relevant preceding claim. 6. A process for producing a β-lactam compound of the following formula: wherein OR¹, R² and R³ are as defined in Claim 1, which comprises reacting an azetidinone compound represented by the following general formula: wherein OR¹ is as defined hereinbefore and X is an electronegative group removable through reaction, with a stannylallene represented by the general formula R²CHßCßCH-SnR⁷₃ (wherein R² is as defined hereinbefore; R⁷ is a C₁ to C₄ alkyl or phenyl group) in the presence of a Lewis acid to give a β-lactam compound of the following general formula: wherein OR¹ and R² are as defined hereinbefore; isomerizing said β-lactam compound by reaction with a base and an organosilyl halide represented by the general formula: (wherein R⁴, R⁵ and R⁶ are as defined in Claim 1; and Y is a halogen), successively, to produce a β-lactam compound of the following general formula: wherein OR¹, R², R⁴, R⁵ and R⁶ are as defined hereinbefore, optionally followed by subjecting said β-lactam compound (9) to a removal reaction of the tri-substituted silyl group. 7. A process as claimed in Claim 6, wherein R⁷ is n-butyl group and X is CH₃COO group. 8. A process as claimed in Claim 6 or Claim 7, wherein the azetidinone compound (6) has a configuration of the following formula: whereby the β-lactam compound (8) has a configuration of the following formula: the β-lactam compound (9) has a configuration of the following formula: the β-lactam compound resulting from removal of the tri-substituted silyl groups has a configuration of the following formula: 9. A process for producing an azetidinone of the formula: (wherein R¹ and R² are as defined in Claim 1) which comprises treating a β-lactam of the formula: wherein OR¹ and R² are as defined in Claim 1 to convert the ethynyl group into a carboxylic acid group.

Inventors: HARUTA, JUNICHI, NISHI, KOICHI, TAMURA, YASUMITSU
Applicants: SHIONOGI & CO., LTD., TAMURA, YASUMITSU
Application year: 1988
Main classification: C07F7
IPC codes: C07D205, C07F7