3- Phenylpropanal, from allyl

Phenylacetonitriles can be induced to undergo Michael reactions with unactivated alkenes. For example, propenylarenes, formed in situ from allylarenes, react with phenylacetonitriles to form 3-aryl-l-cyano-2-methyl-l-phenylpropanes (70-98%) [3] by a procedure analogous to 6.4.1.B, Similarly, the nitriles react with alkynes giving allyl cyanides (80-95%) [38]. 

Chiral (5)-2-(methoxymethyl)-l -[( )-3-phenyl-2-propenyl]pyrrolidine obtained from (S)-2-(meth-oxymethyl)pyrrolidine26,30 and ( )-3-bromo-1-phenyl-1-propene, is deprotonated by potassium rert-butoxide/ferf-butyllithium27-28 generating the chiral allyl carbanion, the alkylation of which affords the enamines, which can be hydrolyzed to give 3-alkylated 3-phenylpropanals. 

Asymmetric Intramolecular Hydrosilation. Intramolecular hydrosilation of allylic alcohols followed by oxidation is a convenient method for the stereoselective preparation of 1,3-diols. An enantioselective version is achieved by use of diene-free BINAP-Rh+ (eq 6). Both silyl ethers derived from cinnamyl alcohol and its cis isomer give (iJ)-l-phenylpropane-l,3-diol in high ee regardless of alkene geometry. 

The major product is cinnamyl acetate (2) a-phenylallyl acetate (3), 1,2-diacetoxy-.3-phenylpropane (4), and fran -propenylbenzene (5) are formed in trace amounts. A similar distribution of allylic acetates is obtained from the solvolysis of cinnamyl-mercuric acetate. C(,H5CH=CHCH2HgOAc, which presumably is the intermediate in the oxidation of allylbenzene. 

Additions of allylic stannanes to aldehydes can also be effected imder high pressure without an added catalyst or promoter [12]. Interestingly, and in apparent contradiction to the thermal additions, mixtures of syn and anti adducts are formed from both (E)- and (Z)-allylic stannanes (Table 3). Moreover, the proportion of (E) syn and (Z) — anti products actually increases as the pressure is increased in contrast with what might have been expected from the thermal reactions. These findings have been interpreted as reflecting reduced activation volumes in the boat vs chair transition states, as illustrated in Eq. (10). The effect is also observed with propanal, 2-ethylbu-tanal, and 2-phenylpropanal. 

Acetone solutions of a large variety of non-stabilized enols with lifetimes from minutes to weeks are now accessible by ruthenium-catalyzed isomerization of allylic alcohols. Preliminary experiments with [Rh(S)-(—)-BINAP(NBD)]C104 demonstrate the potential of this reaction sequence 2-phenyl-2-propenol was transformed into 2-phenylpropanal with 18% ee177. 

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