Stereocontrolled syntheses of the diastereoisomeric 6-(1-hydroxyethyl)-2-ethylthio and 2-(2-aminoethylthio)-penem-3-carboxylates from a common monocyclic azetidinone precursor are described. Cu (I)-promoted cyclisation of suitable N/C-3 secopenems is shown to yield “isopenems” (7-oxo-2-thia-1-azabicyc1o[3.2.0]-hept-3-enes) as the sole bicyclic product.
2-Penem-3-carboxylic acid compounds of the formula ##STR1## in which R.sub.1 represents hydrogen, an organic radical bonded by a carbon atom to the ring carbon atom or an etherified mercapto group and R.sub.2 represents hydroxy or a radical R.sub.2.sup.A forming together with the carbonyl grouping --C(.dbd.O)-- a protected carboxyl group, 1-oxides thereof, as well as salts of such compounds having salt-forming groups, in racemic and optically active form, processes for their preparation, pharmaceutical compositions containing such compounds, and their use as antibiotics, and intermediates and their processes which are useful in the production of the compounds of the formula I.
Chemo- and Regioselective Functionalization of Isotactic Polypropylene: A Mechanistic and Structure–Property Study
作者:Jill B. Williamson、Christina G. Na、Robert R. Johnson、William F. M. Daniel、Erik J. Alexanian、Frank A. Leibfarth
DOI:10.1021/jacs.9b05799
日期:2019.8.14
polyolefin C-H functionalization combined with the development of new reagents enabled the addition of xanthates, trithiocarbonates, and dithiocarbamates to a variety of commercially available branched polyolefins. Systematic experimental and kinetic studies led to a mechanistic hypothesis that facilitated the rational design of reagents and reaction conditions for the thermally initiated C-H xanthylation
The invention relates to 2-penem-3-carboxylic acid compounds of the formula ##STR1## in which R.sub.a represents an organic radical bonded by a carbon atom to the ring carbon atom, a free, etherified or esterified hydroxy or mercapto group or a halogen atom, R.sub.1 represents hydrogen, an organic radical bonded by a carbon atom to the ring carbon atom, or an etherified mercapto group, and R.sub.2 represents a hydroxy group or an R.sub.2.sup.A radical that together with the carbonyl grouping --C(.dbd.O)-- forms a protected carboxyl group, and to salts of such compounds with salt-forming groups, processes for the manufacture of such compounds, pharmaceutical preparations containing compounds of the formula I with pharmacological properties, and their use. The compounds have antibiotic activity.