Nitroalkanes. Roberto Ballini

CH₃NO₂/CH₂Cl₂, Pd₂(dba)₃, ligand, BSA 84 (99%) CH₃NO₂/CH₂Cl₂, Pd₂(dba)₃, ligand, Bu₄NCl/BSA 74 (99%)

Scheme 1.20 Nitroalkanes addition to vinylepoxides under Pd(0) catalysis.

Table 1.7 Two-step process of nitro alkylation of allylic alcohols (selected examples).

Allylic alcohol	Nitroalkane	Yield (%)
		62
		74
		70
		71
		63

      Developing this result, Deardorff et al. [43] reported a two-step process for nitromethylation of allylic alcohols that include (i) the preparation of the corresponding allylic carbonate and (ii) the addition of nitromethane, under Pd₂(dba)₃ catalysis.

So, this procedure represents a useful method for the synthesis of functionalized nitroalkanes and some of the most representative examples are reported in Table 1.7.

      1.6.4 Two-Carbon Homologation of Vinyl Triflates and Bromides

Palladium catalyzes a two-carbon homologation of vinyl bromides (or triflates) via reaction with nitromethane and in the presence of Cs₂CO₃ as base, giving access to homoallylic nitrocompounds (Table 1.8) [44].

      The process exploits the anion stabilizing effect and the leaving properties of the nitro group to generate the homoallylic nitro products via a tandem cross-coupling/π-allylation sequence of the alkenyl derivatives with nitromethane. Following this method a variety of homoallylic nitro compounds can be easily obtained.

Table 1.8 Two carbon homologation of vinyl bromides or triflates (selected examples).

Substrate	Nitroalkane	Yield (%)
		76
		69
		69
		74
		83