Derivatives of 6.beta.-methylpenicillanic acid

Study of the Rh2(OAc)4‐ or BF3·OEt2‐Mediated Reaction of Thioacetic S‐Acid with α‐Diazocarbonyl Compounds

“…In 1977, Sheehan et al reported the photoinduced reaction of 6-diazopenicillinate with thiocarboxylic acids, from which the S-esters were obtained in moderate yields. [6] In 1978, Thomas and coworkers reported the reaction between that same diazo compound and thioacetic acid in the presence of BF 3 ·OEt 2 . In Thomas's case, the corresponding S-ester was isolated in low yield.…”

Preparation of 6α-monosubstituted and 6,6-disubstituted penicillanates from 6-diazopenicillanates: reactions of 6-diazopenicillanates with alcohols, thiols, phenylseleninyl compounds, and allylic sulphides, and their analogues

“…The a-configuration at C-6 was assigned to products (7)-(17) on the basis of their small H(5)-H(6) coupling constants.lz In addition, 6a-methoxypenicillanate (7) was prepared from the known 6a-hydroxypenicillanate (19) by treatment with diazomethane-BF3*Et20.…”

“…As a chemical correlation of the products, the 6a-acetylthiopenicillanate (1 7) was converted into 6a-benzylthiopenicillanate (13). Treatment of the thioester (1 7) with NaOMe-MeOH at -78 "C gave a mixture of the 6a-thiol 2,2,2-trichloroethyl and methyl esters (20) and (21) which were separated by column chromatography, and the trichloroethyl ester alkylated using benzyl bromide in ethanol containing triethylamine. Other reactions of the thiol (20) were not investigated.…”

“…2,2,2-Trichloroethyl 6a-Thiopenicillanate (20).-Sodium methoxide (20 mg) in methanol (10 ml) was added during 1 h to 6a-acetylthiopenicillanate (17) (1 50 mg) in methanol (1 5 ml) at -78 "C under nitrogen, and the mixture stirred for 3 h. The crude reaction mixture was washed with ice-cold dilute HCI, ice-cold aqueous sodium hydrogencarbonate, and icecold water, dried ( MgS04), and concentrated under reduced pressure to give an oil (76 mg) which t.1.c. indicated to contain two major components.…”

The Chemistry of 2‐Azetidinones (β‐Lactams)

“…In addition to the amide group, several different protective groups are used for the transformation of the amino moiety of penicillins and cephalosporins. The amine can be converted into a carbamate group, to give the corresponding Boc [225], Cbz [226] or Teoc [227] derivatives. The Dane protecting group is very suitable for penicillins and cephalosporins, because the proton remaining on the nitrogen is stabilized by hydrogen bonding with the ester carbonyl group, which allows reactions that are normally possible only in doubly protected derivatives [228].…”