Nitroalkanes. Roberto Ballini

Iridium complex, HCOOH/H₂O, pH 2 [34] 94 (R, 92%) Iridium complex, HCOOH/H₂O, pH 2 [34] 92 (R, 90%)

      PMHS, polymethylhydrosiloxane.

      1.6.1 Nitroalkylation of Aryl Halides

Aryl halides can be converted into “aryl nitromethanes” via a cross-coupling reaction with nitromethane, catalyzed by Pd₂(dba)₃, tris(dibenzylideneacetone)dipalladium, as reported in Scheme 1.18 [40].

A more general protocol provides the arylation of primary nitroalkanes (different from nitromethane), via Pd-catalyzed reaction with aryl bromide or chlorides (Scheme 1.19) [41].

      More detailed applications are reported in Chapter 6.

Scheme 1.17 Reductive nitromethylation of aldehydes.

Table 1.5 Nitration of alkanes (selected examples).

Substrate	Nitrating agent	Nitroalkane	Yield (%)
	NHPI (NO2)		63
	NAPI (HNO3)		69
	NAPI (NO2)		69
	NHPI (HNO3)		70
	NHPI (NO2)		54
	NHPI (NO2)		65

      1.6.2 Nitroalkylation of Allylic Esters

Pd catalyzes even the asymmetric allylic alkylation of cyclic allyl esters [42] in the presence of O,N-bis-trimethylsilylacetamide (BSA) as base and a chiral biphosphine ligand (Table 1.6). The method allows a practical way to primary chiral nitroalkanes with an extra carbon atom.

      1.6.3 Nitroalkylation of Allylic Alcohols

Unactivated nitroalkenes (mainly nitromethane) can be added to vinyl epoxides, under Pd(0) catalysis, affording nitroalkenols (Scheme 1.20).

Scheme 1.18 Nitromethylation of aryl halides.

Scheme 1.19 Nitroalkylation of aryl halides.

Table 1.6 Asymmetric nitromethylation of cyclic allyl esters (selected examples).

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Substrate	Reaction conditions	Nitroalkane	Yield (%), (ee)
	CH3NO2/CH2Cl2, Pd2(dba)3, ligand, BSA		82 (99%)
	CH3NO2/CH2Cl2, Pd2(dba)3, ligand, Bu4NCl/BSA		99 (99%)