C–C Bond Formation
2.5
327
⊡ Scheme 39
⊡ Scheme 40
⊡ Scheme 41
tone nucleosides [58,64]. 2 -Deoxy-3 -diazoacetates of nucleosides 154a–d (R 1 =H, COMe,
CO 2 Me, CO 2 Et) were chosen as templates for the insertion reactions. Initial studies on
stereocontrolled C,H-insertion of 2 -deoxy-3 -α-diazoacetate nucleosides were performed in
the presence of dirhodium tetraacetate (1.0 mol%) in dichloromethane at room temperature
and only a trace amount of product was obtained. However, when the reaction mixture was
refluxed, γ -butyrolactones 155a–d were obtained with high diastereoselectivities in 58–80%
yields.
2.5
327
⊡ Scheme 39
⊡ Scheme 40
⊡ Scheme 41
tone nucleosides [58,64]. 2 -Deoxy-3 -diazoacetates of nucleosides 154a–d (R 1 =H, COMe,
CO 2 Me, CO 2 Et) were chosen as templates for the insertion reactions. Initial studies on
stereocontrolled C,H-insertion of 2 -deoxy-3 -α-diazoacetate nucleosides were performed in
the presence of dirhodium tetraacetate (1.0 mol%) in dichloromethane at room temperature
and only a trace amount of product was obtained. However, when the reaction mixture was
refluxed, γ -butyrolactones 155a–d were obtained with high diastereoselectivities in 58–80%
yields.