Synthesis of Some New Azetidinone Derivatives Containing Aryl Sulfonyloxy Group

Some novel azetidinone derivatives containing aryl sulfonyloxy group have been prepared. The 4-sulfonyloxy aniline derivative (2) has been prepared by reaction of 4-nitro phenol (sodium salt) with N-acetyl sulfanilyl chloride (ASC) followed by hydrolysis by ethanolic HCl. This compound (2) undergoes facile condensation reaction with aromatic aldehydes to yield different Schiff’s bases (3a-h). Cyclocondensation of compounds (3a-h) with chloro acetyl chloride yields different 2-azetidinone derivatives (4a-h).


I Introduction ntroduction
2][3][4] Azetidine-2-ones also have great importance because of the use of β-lactam derivatives as an antibacterial agents. 5The antibiotic activity is closely related to the substituted β-lactam ring structure. 6More particularly and recently these types of compounds have been found in the treatment of T.B. and other chemotherapeutic diseases. 7The area in which this type of compound containing arylsulfonyloxy group (ArSO 3 ) has not received attention in spite of well defined antibacterial activity of sulfonyl group. 8ence it was thought interesting to synthesize novel azetidinone derivatives containing aryl -SO 3 group.The present paper comprises the synthesis and characterization of azetidinone derivatives as shown in S Scheme cheme --1 1.

E Experimen xperimental tal
Melting point was taken in open capillary tubes and are uncorrected.The synthesized compounds were characterized by IR spectroscopy, thin layer chromatography and elemental analyses of C,H, and N. The IR spectra were recorded in KBr pellets on a Nicolet 400D spectrometer and 1 H NMR spectra in CDCl 3 /DMSO on Hitachi R-1500, 60MHz spectrometer using TMS as a internal standard.TLC was performed on silica gel layer and spots were visualized by exposing the developed spots and dry plates to I 2 vapours.The required 4-acetamide benzene sulfonyl chlorides was prepared by reported method. 9ll chemicals used were of laboratory grade.

Typical procedure
The compound (1) was hydrolyzed by refluxing with 75ml of ethanol containing 15ml of conc.HCL for 4-5 hrs.It was then poured into ice-cold water and finally made just alkaline with liq.ammonia.The resultant hydrolyzed product ( 2) is filtered off and washed with water and dried.It was then recrystalized from ethanol to give product in 65-75% yield.Melting point of the compound (2) was found to be 105 o C.

Preparation of schiff's bases (3a-h)
Typical procedure : A mixture of equimolar amount of hydrolysis product (2) (0.01mole) and different aromatic aldehydes (0.01mole) in 50ml acetic acid was refluxed for about 10hrs on oil bath.The reaction mixture was cooled and it was poured into ice water and the solid obtained was filtered and recrystalized from ethanol to give yellowish white products (3a-h) in 50-55% yield.

Preparation of Azetidinone derivatives (4a-h).
Typical procedure : A mixture of different schiff's bases (3a-h) (0.002 mole) and triethylamine (TEA) (0.004 mole) was dissolved in 1,4-dioxane (50 ml) and cooled and stirred.To this well stirred cooled solution chloro acetyl chloride (0.004 mole) was added drop wise within a period of 20 minute.The reaction mixture was then stirred for further 3hrs and then refluxed for 8 hrs.The resultant mixture was concentrated, cooled, then poured into ice-cold water and then extracted with ethyl acetate.The solvent was evaporated and the product thus obtained was purified by column chromatography over silica gel using 15% ethyl acetate: 85% benzene as eluent.Recrystallization from ether/ n-hexane yields Azetidinone derivatives (4a-h) in 50-55% yield.

R Result and Discussion esult and Discussion
The synthesis of Azetidinone derivatives is accomplished as shown in the S Scheme cheme --1 1. Analytical and spectral data are given in T Table able --1 1.It was observed that N-acetyl sulfanilyl chloride on reaction with sodium salt of 4-nitrophenol give 4-(4'nitro phenyl sulfonyloxy) acetanilide (1).Its structure was established on the basis of their elemental analysis and IR spectra showing bands at 1210 -1150 cm -1 (SO 3 ) and 1550 cm -1 (CONH).Compound (1) was easily hydrolyzed 10 with EtOH/HCl to give compound (2).The hydrolyzed product (2) have consistent value of C.H.N and S contents with predicated structure.Also compound (2) shows the diazo test for primary amine (-NH 2 ) group.The IR spectra of (2) show absorption bands at 3390 & 3410 cm -1 (NH 2 ) and 1210-1150 cm -1 (-SO 3 ).The compound (2) was also confirmed by 1 HNMR spectra showing peaks of NH 2 at 4.20 and 7.2-8.3for aromatic protons.The above compound (2) on condensation with different aromatic aldehydes in acetic acid yielded different schiff's bases (3a-h).The structures of (3a-h) were confirmed, by elemental analysis and the IR spectra showing absorption band at 1640-1620 (-C=N).
The cyclocondensation reaction of compounds (3a-h) with chloro acetylchloride in dry dioxone in presence of triethylamine (TEA) as catalyst resulted in formation of 2-azetidinones 11 (4a-h).The structure assigned to (4a-h) were supported by elemental analyses and IR spectra showing absorptions bands at 1750 -1740 (C= 0 of monocyclic â-lactam).The structures were also confirmed on the basis of 1 Scheme Scheme --1 1 Sodium salt of 4-nitro phenol (0.05 mole) was dissolved in mixture of 40ml anhydrous acetone and 1ml of dry pyridine in 250ml R.B. flask and 11.67 gm (0.05 mole) of pure 4-acetamido benzene sulfonyl chloride (ASC) was added portion wise with stirring.Sodium bicarbonate (0.05 mole) was added as an acid acceptor.The reaction mixture is set aside overnight and almost pure 4-(4'nitro phenyl sulfonyloxy) acetanilide is filtered off and washed with cold water and air-dried.It was then recrystalized from ethanol to give whitish yellow product in 60-70% yield.Melting point of the compound (1) was found to be 190 0 C.

Table Table
HNMR spectrum.