Nitro alkanes allylation

Although the unsaturated nitrile oxides 124 can be prepared via the aldoxime route (see Scheme 8), the older procedure suffers from the disadvantage that a tenfold excess of allyl alcohol and two additional steps are required when compared to Scheme 15. Therefore, unsaturated nitro ether 123 that can be prepared by condensation of an aldehyde 120 and a nitro alkane followed by Michael addition of alcohol 122, was a useful precursor to nitrile oxide 124 [381. The nitrile oxide 124 spontaneously cyclized to ether 125. This procedure is particularly suitable for the synthesis of tetrahydrofurans (125a-h) and tetrahydropyrans (125i-k) possessing Ar substituents in 72-95% yield (Table 12). The seven-membered ether 1251 was obtained only in 30% yield on high dilution. The acetylenic nitro ether 126 underwent INOC reaction to provide the isoxazole 127. 

Proton acceptor. In the displacement reaction of allyl carbonates with nitro-alkanes, the presence of this silylated acetamide affords good diastereoselectivity. 

The a-C-alkylation of nitro-alkanes is a valuable synthetic reaction but is limited due to a propensity for O-alkylation. The circumvention of this problem has been addressed (Vol. 5, p. 197 Vol. 6, p. 207), and coincidentally two reports of a new alternative procedure for a-C-allylation of nitro-alkane monoanions, using palladium catalysis, have appeared (Schemes 36 and 37)i88,i69... 

Type IV (spectators to CM) 1,1-Disubstituted olefms " 1,1-Disubstituted olefms, disub. o ,/ -unsaturated carbonyls, 4° allylic carbon-containing olefins, perfluorinated alkane olefins, 3° allylamines (protected)" Vinyl nitro olefins, protected trisubstituted allyl alcohols, a,/ -olefin of 2-subst. 1.3- butadienes, a,/ -olefm of electronically deactivated 1.3- butadienes ... 

Halogen-El8,1044 (In + Allyl-Hal) Nitro- E21c, 2619 (1,3-Dien + N02 —Alkan)... 

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