Copper(I) catalysis of olefin photoreactions. 9. Photobicyclization of .alpha.-, .beta.-, and .gamma.-alkenylallyl alcohols

Fluorinated Analogues of Amicetose and Rhodinose – Novel Racemic and Asymmetric Routes

“…The solvent was evaporated in vacuo, and the silica gel mixture was dried under vacuum at room temperature for 1 h. The mixture was cooled to -78°C, and a stream of dry O 3 was carefully passed upwards through the silica gel supported by a frit in a U-shaped tube. After 1 h, the mixture was purged with O 2 and N 2 , eluted from the silica with methanol (50 mL), quenched with dimethyl sulfide (0.5 mL) and stirred for 6 h. [46] ( -)-(2S,3R)-1,2-Epoxyhept-6-en-3-ol (31) and (+)-(2R,3R)-2,3-Epoxyhept-6-en-1-ol (32): Titanium tetraisopropoxide (4.79 mmol, 1.50 mL), (-)-diisopropyl -tartrate (5.36 mmol, 1.15 mL), dienol 30a (50 mmol, 5.6 g) and tert-butyl hydroperoxide (49.5 mmol, 15 mL of a 3.3  solution in toluene) were added successively to a stirred suspension of powdered molecular sieves (4 Å) in cold (below -20°C) dry CH 2 Cl 2 (100 mL). The mixture was stirred in the freezer below -20°C for 15 d, then the mixture was filtered through filter paper into a cold (0°C) solution of ferrous sulfate (72 mmol, 20 g) and tartaric acid (40 mmol, 6 g) in water (60 mL).…”

Addition Polymers of Strained Cyclic Olefins – Transition Metal Catalysed Polymerisations of the Cyclobutene Derivative Bicyclo[3.2.0]hept‐6‐ene

“…The signal for C 2 of the exo structure appears at d ¼ 32.9-33.2 ppm whereas the signal for C 2 of the endo structure is shifted upfield to d ¼ 27.2-27.3 ppm. [25] Thus, an endo-enchained unit of poly(6,7-bicyclo[3.2.0]heptylene) would produce a 13 C NMR signal for C 2,4 that would be expected to overlap with the C 3 signal range of d ¼ 28.5-25.8 ppm. Accordingly, the C 2,4 to C 3 signal intensity ratio would be less than the observed value of 2.0/1.0 if both endo and exo structures were present in the polymer.…”

Synthesis of cyclobutane fused γ-butyro lactones through intramolecular [2+2] photocycloaddition. Application in a formal synthesis of grandisol

“…The latter reaction is believed 11 to proceed through a tricordinated Cu(I) complex 13a. However, an analogous Cu(I) complex 13b with the bulkier OEt group occupying an endo position, necessary for formation of the endo-adduct 15b, would be highly sterically crowded.…”