4- -2-azetidinone

The reaction of alkenyl mercurials with alkenes forms 7r-allylpalladium intermediates by the rearrangement of Pd via the elimination of H—Pd—Cl and its reverse readdition. Further transformations such as trapping with nucleophiles or elimination form conjugated dienes[379]. The 7r-allylpalladium intermediate 418 formed from 3-butenoic acid reacts intramolecularly with carboxylic acid to yield the 7-vinyl-7-laCtone 4I9[380], The /i,7-titisaturated amide 421 is obtained by the reaction of 4-vinyl-2-azetidinone (420) with an organomercur-ial. Similarly homoallylic alcohols are obtained from vinylic oxetanes[381]. [Pg.81]

Cis-3-(I,I-dimetliyletliyl)-4-phenyl-2-azetidinone Quaternary ammonium derivative of 3,5-Dinitro- [82] [82]... [Pg.6]

NYL CHLORIDE AND 2 AZETIDINONE 4 4-dimethyl, 46,51 2- Azetidmones, preparation of, 46,56 o Azidobiphenyls, decomposition to m-trenes and cyclization to carba-zoles, 46, 88... [Pg.121]

Benzyl-4-phenyl-2-azetidinone (17, R1 = H R2 = C6H5 R3 = Bn) Typical Procedure26 ... [Pg.557]

R = C6H5 (3S,4R)-3-[(R)-t-(4-nitrophenylmethoxycarbonyloxy)ethyl -4-(phenyhhiocarbonylmethyl)-l-trimethylsilyl-2-azetidinone 05 yield 93%... [Pg.832]

Uans-3-[(S)-t-(lert-buiyldimethylsilyloxy)ethy[i-4-[3-diazo-4-(4-nitrophenylmethoxy)-2,4-dioxobuty[ -2-azetidinone 01 yield 83%... [Pg.832]

S,4/ )-3-[(/ )-l-(rm-Butyldimethylsilyloxy)ethyl]-4-(2-propenyi)-2-azetidinone Typical Procedure1,2 ... [Pg.834]

To a stirred solution of 1 g (3.48 mmol) of (3R,4R)-4-acetoxy-3-[(R)-l-(( Tt-butyldimethylsilyloxy)ethyl]-2-azetidinone in 20 mL of CH2C12 are added 1.46 g (5.17 mmol) of tetrakis(2-propeny])tin and 49.5 mg (0.348 mmol) of BF3 0(C2H5)2 under a nitrogen atmosphere. After stirring for 15 h at 20 °C, CH2C12 is added and the mixture is washed three times with water and then dried over MgS04. The solvent is removed in vacuo and the residue is purified by flash chromatography (cyclohexane/ethyl acetate 2 1) yield 800 mg (85%) nip 70-77 °C. [Pg.834]

S-trans)-1 -benzyl-oxy-3 teii,-butyl-oxycarbonylomino 4-methyl-2-azetidInone... [Pg.169]

R,4S)-1 -tert-butoxy-corbonyl-3-(1 -ethoxy-elhoxy)-4-phenyl-2-azetidinone (XXI)... [Pg.695]

CjjHjoOioSi 115437-18-8) see Paclitaxel [(triethylsilyl)oxy]acetic acid ethyl ester (C oH220jSi) see Paclitaxel c -3-(triethylsilyloxy)-4-phenyl-2-azetidinone (Ci3H23N02Si) see Paclitaxel trifluoroacetic anhydride... [Pg.2449]

GjHjiOjP 116-17-6) see Clodronate disodium (3/t,45)-3-(triisopropylsilyloxy)-4-phenyl-2-azetidinone (C nH2()N02Si 132127-31-2) see Docetaxel triisopropylsilyl trifluoromethanesulfonate (C ()H2 F303SSi 80522-42-5) see Tacrolimus... [Pg.2451]

The anomalous behaviour observed in attempted 1-deprotection of certain 4-heteroarylmethyl-l-(4-methoxyphenyl)-2-azetidinones by the action of CAN has been investigated further <961771 > and evidence obtained to support the mechanism proposed, which involves the intermediate 47 when the 4-substituent is the tetrazolylmethyl group as in 46 <96T10169>. Use of the novel enzyme, o-phthalyl amidase, as a deprotection agent for P-lactams has been developed <96MI875>. [Pg.71]

Reactions of carbenoids with 4-thio-substituted 2-azetidinones have attracted much interest recently. Insertion of the carbene unit derived from diazomalonic esters 297-34°> or ethyl diazo(diethoxyphosphoryl)acetate 340 into the C4—S bond of simple P-lactams 353 and 354 took place irrespective of whether a N—H or a N—R... [Pg.214]

The sulfonium ylide derived chemistry of penicillins continues to meet the interest of several research groups. It is well known that intermolecular carbenoid attack at the sulfur atom generates a sulfonium ylide which undergoes spontaneous opening of the thiazolidine ring to furnish a l,2-sm>-penicillin 326). Novel examples of this reaction type were found upon Rb2(0Ac)4-catalyzed decomposition of diazomalonic esters in the presence of various penicillins this transformation constituted the opening step of a synthetic sequence directed towards 2-alkoxycarbonyl-cephems 345 a) or modified penicillins 345 b). Similar to its reaction with 4-thio-2-azetidinone... [Pg.216]

The same group has developed the enantiospecffic synthesis of a-hydroxy [5-lactams 224 from readily available carbohydrates (Scheme 9.72) [123]. Microwave-assisted chemical reactions have been utilized for the preparation of these 3-hydroxy-2-azetidinones 224 and their subsequent conversion to enantiomeric forms of intermediates for natural products. [Pg.337]

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