Allylcyanocuprates from Butylallyltellurides

Abstract

Lithium diallylcyanocuprates generated by reaction of allyl halides with lithium n-butyltellurolate followed by transmetalation with lithium dibutylcyanocuprate react with vinyl triflates leading to highly unsaturated hydrocarbons.

Synthesis of (R)-(+)-4-Methylcyclohex-2-ene-1-one

“…The dried solution was filtered, and the filtrate was concentrated to afford the vinyl triflate 9 as a pale yellow oil. 1 H and 13 C NMR spectroscopic data for 9 prepared in this way were in agreement with those reported …”

“…1 H and 13 C NMR spectroscopic data for 9 prepared in this way were in agreement with those reported. 23 Step 2: Synthesis of α-(Trifluoromethanesulfonyloxy)-α,β-unsaturated Ketone 10. The residue obtained in the preceding step was dissolved in dichloromethane (220 mL) and methanol (54 mL), and the resulting solution was cooled to −78°C.…”

“…23 The unpurified vinyl triflate 9 was selectively oxidized (ozone, dichloromethane−methanol, −78°C) to form the α-(trifluoromethanesulfonyloxy)-α,β-unsaturated ketone 10. Heating solutions of the unpurified α-(trifluoromethanesulfonyloxy)-α,β-unsaturated ketone 10 with palladium acetate (2 mol %), triphenylphosphine, triethylamine, and formic acid provided the target 1 (44%, >99% ee from 3).…”

“…We have developed an alternative and highly practical route to ( R )-(+)-4-methylcyclohex-2-ene-1-one ( 1 , Scheme ). Deprotonation of ( R )-(+)-pulegone ( 3 , lithium hexamethylsilazide) and trapping of the resulting enolate with N -phenyl-bis(trifluoromethanesulfonimide) provided the vinyl triflate 9 . The unpurified vinyl triflate 9 was selectively oxidized (ozone, dichloromethane–methanol, −78 °C) to form the α-(trifluoromethanesulfonyloxy)-α,β-unsaturated ketone 10 .…”

Reduction of alkyl and vinyl sulfonates using the CuCl2·2H2O–Li–DTBB(cat.) system

“…Stirring was maintained during 9 h. After solvent removal at the rotatory evaporator, the resultant yellow oil was purified by column chromatography on silica gel (hexane) to yield the enol triflate product. The following known compounds, included in Table 2, were characterized by comparison of their chromatographic and spectroscopic data ( 1 H and 13 C NMR, and MS) with those described in the literature: (Z)-1-butyl-1-pentenyl trifluoromethanesulfonate (entry 1), 36 4-tert-butylcyclohexen-1-yl trifluoromethanesulfonate (entries 2 and 3), 35 trans-3,4,4a,5,6,7,8,8a-octahydronaphthalen-1-yl trifluoromethanesulfonate (entry 4), 9b 3-methyl-6-(1-methylethylidene)cyclohexen-1-yl trifluoromethanesulfonate (entry 6), 37 3,5,5-trimethyl-1,3-cyclohexadien-1-yl trifluoromethanesulfonate (entry 7). 38 For new compound, physical and spectroscopic data follow.…”