Phenylprop-2-en-l-ol

Aldehyde Organomagnesium compound Product isolated (yield, %) Ref. 

4-Me2NC6H4CHO 2-MeOC,H4MgBr 2-MeOC6H4 CHOH (57-58) 4-Me2NC6H4 H2C=CHCH2CH(OH)CH=CH2 [27] 

PhCH=CHCHO MeMgBr OH (59-64) PhCH=CHCH=CH2f (72-75) [29] 

A solution of heptylmagnesium bromide (3 mmol) in THF is stirred under nitrogen at -95° as a solution of 2-(phenylseleno)-3-(trimethylsilyl)propanal (2 mmol) in THF (1 ml) is added during 15 min. The mixture is stirred at -95° for 2.5 h and at -60° for 0.5 h. Saturated aqueous ammonium chloride (2 ml) is added and the mixture is allowed to 

The stereochemistry of the product was established by elimination to give ( )-1 -(trimethyIsilyl)dec-2-ene. 

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An acyclic enone, 2-ethyl-l-phenylprop-2-en-l-one, was reduced with the yeast Pichia stipitis CCT 2617 [19cj. The reduction proceeded chemo- and enantioselec-tively to afford (S)-2-ethyl-l-phenylprop-2-en-l-ol (65% yield, >99% ee). XAD-7 was used to decrease and control the concentration of both the substrate and the product (Figure 8.25). 

The UV spectrum of l-phenylprop-2-en-l-ol shows an intense absorption at 220 nm and a weaker absorption at 258 nm. When this compound is treated with dilute sulfuric acid, it rearranges to an isomer with an intense absorption at 250 nm and a weaker absorption at 290 nm. Suggest a structure for the isomeric product and propose a mechanism for its formation. 

Normally the chiral auxiliaries are introduced and removed in the asymmetric synthesis of Simmons-Smith reactions of allylic alcohols to provide mostly /rani-disubstituted cyclopropanes. Stereoselective syntheses of c -disubstituted cyclopropanes are difficult to achieve. Starting from (Z)-3-phenylprop-2-en-l-ol (80a) and (Z)-6-phenylhex-2-en-l-ol (80b), the corresponding c -disubstituted cyclopropanes 81a and 81b were prepared by first treating them with diethylzinc followed by diethyl (- -)-(/ ,7 )-tartrate (DET). A zinc-bridged intermediate is assumed to be formed first. This is subsequently treated with diethylzine and diiodomethane to give the products 81. The reaction conducted at — 12 "C gave the cyclopropanated products 81a and 81b with 70 and 81% ee, respectively.This method has the advantages that the introduction of the chiral auxiliary to the substrate and its removal are not neccessary and that both cis- and trans-disubstituted cyclopropanes could be prepared from (Z)- and ( )-allylic alcohols, repectively. 

We have further examined the reactions of thiolato-bridged diruthenium complexes with other unsaturated organic substrates. When the cationic Ru complex 4 is treated with cinnamyl alcohol in p-xylene, the allylated aromatic compound 18 is obtained in good yield (Equation 6). We assume a Tc-allyl intermediate because the reaction using l-phenylprop-2-en-l-ol gives, instead of cinnamyl alcohol, the same product 18 however, the detailed reaction mechanism is still obscure. This novel allylation reaction is halogen-free, and may replace the conventional Friedel-Crafts alkylation. 

Ketones and aldehydes are reduced by silanes in acid media, as in the reaction of cyclohexanone with Et3SiH and trifluoroacetic acid to give cyclohexanol in 74% yield. The reaction is selective for 1,2-reduction of aldehyde moieties, as in the reduction of 3-phenyl-prop-(2 )-enal to 3-phenylprop-(2 )-en-l-ol in... 

Reaction performed in MeOH under 14 bar of H2 (selectivity of 99% in 3-phenylprop-2-en-l-ol). 

Then, the stereoselective substitution reaction of cation (42) by water generated 1-phenyl prop-2-en-l-ol (44) and/or ( )-3-phenylprop-2-en-l-ol (45). Finally, (37) assisted by FeCl2 oxidized (44) or (45) to the product (ii)-3-phenylprop-2-enal (46). The cleavage of the allyl sp C-H bond in the rate-determining step was supported... 

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