Resolution and absolute configuration of bicyclo[3.3.0]octa-2,6-diene-2-carboxylic acid

Abstract

Thermolysis of Benzo[c ]fluorenone 13a. A solution of 0.17 mmol of 13a, dissolved in 20 mL of diphenyl ether, was thermolyzed at 250 °C in the dark during 18 h. Preparative TLC on silica gel with benzene-hexane (4:1), after removal of the diphenyl ether as usual, yielded besides 13a, a red product; recrystallization from heptane afforded 0.13 mmol of the benzo[c]fluorenone 16 (77%): mp 193 °C; IR 1690 cm"1 (pc=0); lH NMR (CDClg/ ) 2.53/0.35 (3, s, 5-CH3), 2.72/-0.03 (3, s,, 3.86/0.66 (3, s,

Synthesis and reactivity of 1-sulfonylcyclooctatriazoles

“…Enantiomeric excess was determined by HPLC analysis following LiAlH 4 reduction; or the intermediate sulfonyl imine was hydrolysed to the ketone 23 using basic Al 2 O 3 and converted to the tertiary alcohol 24 by nucleophilic addition of PhMgBr (>20 : 1 dr by 1 H NMR, Scheme 2). Accessing known ketone 23 28 allowed further confirmation of the absolute stereochemistry. The second workup was essential in cases where the sulfonamide enantiomers 22 could not be separated by HPLC or functionality was incompatible with LiAlH 4 reduction ( i.e.…”