Reactions of (E)-beta-nitrostyrenes 1 and triethylborane 2 or tricyclohexylborane 4 in THF solution at room temperature in the presence of oxygen in the air as radical initiator generate high yields of trans-alkenes (E)-3 or (E)-5. Medium to high yields of different (E)-alkenes (E)-5, 7, 10, 12, and 14 also can be prepared when 1 reacts with different radicals, prepared from secondary alkyl iodides 6 and 8 or tertiary alkyl iodides 9, 11, and 13, in the presence of 2 and air as radical initiator. The generation of the only product (E)-alkenes can be explained by the generation of the benzylic radical A and/or B as the intermediate only and the mechanism is similar to Scheme 1. Both (E)- and (Z)-16a-c are generated when (E)- and (Z)-15a-c are used to react with adamantyl radical under similar conditions. Only (Z)-16d was observed when either (E)- or (Z)-15d was used to react with adamantyl radical. The generation of the (E)- and/or (Z)-alkenes can be explained by the free rotation of the A and/or B to generate A' and/or B' and vice versa, and the mechanism is proposed to be a free-radical reaction via NO2/alkyl substitution and is shown as Scheme 2.
Photolysis of t‐BuHgCl/KI with PhC(R2)C(R1)NO2 forms PhC(R2)C(R1)Bu‐t when R1 = R2 = H or in low yield when R1 = H, R2 = Ph. When R1 ≠ H, or when R2 = Ph, reactions with t‐BuHgI/KI/hv proceed mainly via PhC(R2)C(R1)NO2·‐, PhC(R2)C(R1)N(OBu‐t)O−HgX+, PhC(R2)C(R1)NO and PhC(R2)C(R1)N(OBu‐t)HgX to form a variety of novel products including the dimeric bisnitronic esters (6) with R1 = Me or Ph and R2 = H; PhCH(R2)C(R1) = NOBu‐t with R1 = Me or Ph and R2 = H or R1 = H and R2 = Ph; PhC(R2)(OBu‐t)C(R1)NOH with R1 = H or Me and R2 = Ph; and 3‐phenyl‐2‐R1‐indoles with R1 = H, Me, Ph, PhS or t‐BuS and R2 = Ph. Nitrosoaromatics react with t‐BuHgX in the dark to form ArN(OBu‐t)(OBu‐t)HgX+ which condenses with ArNO to form the azoxy compound. tert‐Butyl radicals will add to RNO2 [R = Ph, Ph2CCH, Ph2CC(Ph)] in the presence of t‐BuHgI2− to form products derived from RN(OBu‐t)O−HgI+.
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