Allylic phosphorates rearrangement

Beckman rearrangement of the oxime of 7-ketodehydroabietate with phosphoric acid gives the expected lactam (50) and a decarbonylated amine (51). The dihalocarbene adduct of methyl abietate is formed " across the 7(8) double bond. The photo-oxidation of methyl isopimarate, which has a A -double bond, gives 7a-hydroxysandaracopimaric acid methyl ester. However, in the pimaric acid series both the 7a- and 14a-allylic alcohols are formed. 

Pudovik. A.N.. and Aladzheva, I.M., Thermal or pseudo-Claisen rearrangement of allyl and propargyl esters of phosphorous acid, Dokl. Akad. Nauk SSSR, 151, 1110, 1963 Dokl. Chem. (Engl. Transl.), 151, 634, 1963. 

The bulkier 1,2-epoxyoctane can be rearranged over zeolites HY (Si/Al = 15) and H-OFF (Si/Al 3.6) at 160 °C in an autoclave, with toluene as solvent this results in 45 % and 46 %, respectively, seleetivity to octanal 17 %/25 % to allylic alcohols, and 18%/14% to aldolization products, e. g. 2-/z-hexyldec-2-en-l-al [21], A kinetic study of this reaction over different acidic heterogeneous catalysts, e. g. phosphoric acid, ZnCU immobilized on various supports, sulfated zirconia, zeolites, and dodecatungstenophosphoric acid, was reported by Yadav and Satoskar [22],... 

Rueping and Antonchick [51] have examined the phosphoric acid diester-catalyzed 2-aza-Cope rearrangement [52], a transformation that provides an efficient entry to chiral homoallylic amines. They assumed that a phosphoric acid diester would both promote the in situ formation of an allyl iminium cation from an aldehyde and an achiral homoallylic amine, and the subsequent 2-azonia-Cope rearrangement. In a separate hydrolysis step, the rearranged homoallylic amine would furnish the target chiral amine (Scheme 40.42). 

The requisite hemiaminal vinyl ethers were stereoselectively obtained by a Ni(ll)-catalyzed double-bond isomerization of the readily available heiniairiinal allyl ethers. The authors found that the rearrangement could be efficiently catalyzed by means of the BINOL-derived phosphoric acid diester (R)-30 (Scheme 40.46). Owing to the unstability of the resulting aldehydes, they were subsequently reduced to the corresponding y-amino alcohols. 

Scheme 40.51 Phosphoric acid dIester-catalyzed enantloselective semipinacol rearrangement of 2-oxo-allylic alcohols.

In 2009, the catalytic enantioselective semipinacol rearrangement of 2-oxo allylic alcohols 83 was detailed by Zhang et al., leading to enantioenriched spiro-ethers 84 in a single operation (Scheme 2.24). They found that both phosphoric acids 5b and silver phosphate 5i were optimal catalysts, while the latter probably underwent silver-proton exchange with hydroxyl group of subsnates in the catalytic procedure [35],... 

Subsequently, the same group demonstrated an asymmetric synthesis of 3-amino aldehydes via catalytic double-bond isomerization/enantioselective aza-Petasis-Ferrier rearrangement reaction (Scheme 2.93) [128]. Similarly, the hemiaminal allyl ether substrates 346 were first isomerized by Ni(II) complexes to stereoselectively form Z-configured vinyl ethers 347, which then underwent a phosphoric acid-catalyzed... 

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