Substrate cinnamyl alcohol

In order to avoid polymerization and to achieve better stereocontrol by quasi-intramolecular addition, a carbanion-stabilizing group and a complexing substituent for capturing alkyllithium/(—)-sparteine in the substrate are useful. This carbolithiation protocol was realized with great success by Marek, Normant and coworkers (equation 125) Addition of n-BuLi/(—)-sparteine (11) onto the lithium alcoholate derived from ( )-cinnamyl alcohol (457) in cumene at 0°C afforded the addition product with 82% yield and 80% ee. 

Two of the commonest models are benzyl and cinnamyl alcohols - the former because it is easily oxidised beyond benzaldehde to benzoic acid and the latter because its double bond is often attacked, so that oxidation to cinnamaldehyde would show that the oxidant is mild enough to avoid competing double-bond attack. Geraniol is also included as a model substrate as it is in the same category as cinnamyl alcohol. Since there are so many examples of smdies on their oxidations a limited selection only is given. 

Here we report the synthesis and catalytic application of a new porous clay heterostructure material derived from synthetic saponite as the layered host. Saponite is a tetrahedrally charged smectite clay wherein the aluminum substitutes for silicon in the tetrahedral sheet of the 2 1 layer lattice structure. In alumina - pillared form saponite is an effective solid acid catalyst [8-10], but its catalytic utility is limited in part by a pore structure in the micropore domain. The PCH form of saponite should be much more accessible for large molecule catalysis. Accordingly, Friedel-Crafts alkylation of bulky 2, 4-di-tert-butylphenol (DBP) (molecular size (A) 9.5x6.1x4.4) with cinnamyl alcohol to produce 6,8-di-tert-butyl-2, 3-dihydro[4H] benzopyran (molecular size (A) 13.5x7.9x 4.9) was used as a probe reaction for SAP-PCH. This large substrate reaction also was selected in part because only mesoporous molecular sieves are known to provide the accessible acid sites for catalysis [11]. Conventional zeolites and pillared clays are poor catalysts for this reaction because the reagents cannot readily access the small micropores. 

The second stoichiometry consideration is the ratio of catalyst to substrate. As noted in the preceding section, virtually all asymmetric epoxidations can be performed with a catalytic amount of Ti-tartrate complex if molecular sieves are added to the reaction milieu. A study of catalyst/substrate ratios in the epoxidation of cinnamyl alcohol revealed a significant loss in enantioselectivity (Table 6A.2) below the level of 5 mol % catalyst. At this catalyst level, the reaction rate also decreases, with the consequence that incomplete epoxidation of the substrate may occur. Presendy, the recommended catalyst stoichiometry is from 5% Ti and 6% tartrate ester to 10% Ti and 12% tartrate ester [4],... 

The concentration of substrate used in the asymmetric epoxidation must be given consideration because competing side reactions may increase with increased reagent concentration. The use of catalytic quantities of the Ti-tartrate complex has greatiy reduced this problem. The epoxidation of most substrates under catalytic conditions may be performed at a substrate concentration up to 1 M. By contrast, epoxidations using stoichiometric amounts of complex are best run at substrate concentrations of 0.1 M or lower. Even with catalytic amounts of the complex, a concentration of 0.1 M may be maximal for substrates such as cinnamyl alcohol, which produce sensitive epoxy alcohol products [4]. 

It has been reported that reaction of n. 3-unsatu rated carboxylic acids with bis(collidine)bromine(l) hexafluorophos-phate leads to the formation of 2-oxetanones in moderate yields (Equation 33) <1999JOC81>. As with the related reaction of cinnamyl alcohols (discussed in Section 2.05.9.1), this 4- electrophilic intermediate. The cyclization reaction was diastereospecific single (E)- or (Z)-isomers were reacted to give single stereoisomeric products. Lactonization was favored by substrates that were /3-dialkyl-substituted, or ct-alkyl/aryl-, /3-aryl-substituted on the C-C double bond. ct-Monoalkyl/aryl, /3-unsubstituted substrates gave either polymeric products or exclusive vinyl bromide formation. 

Figure 6.5 Variation in the RH measured during the esterification reaction of butyric acid with different alcohols cinnamyl alcohol ( ), 1-phenyl-1-butanol ( ), and Z-L-Ser-OBzl (A). Experimental conditions 2 ml of toluene, 20 mg of lyophilized mycelia, and 50mM equimolar substrates in a 6ml sealed vial.

M or lower. Even with catalytic amounts of the complex, a concentration of 0.1 M may be maximal for substrates, such as cinnamyl alcohol, which produce sensitive epoxy alcohol products. ... 

Nevertheless, the substrate specificity of peroxidases is so wide that secretory plant peroxidases are capable of accepting a plethora of natural compounds as substrates, such as indoles [43], porphyrins [44,45] including chlorophylls [46,47], terpenoids such as lutein [48], unsaturated lipid acids such as linoleic acid [49], alkaloids [50-52] including betacyanins [53], phenolics such as benzoic acids [54,55], DOPA [56], coumarins [38,57], stylbenes [58], catechins [36,59], chalcones [60], flavonols [61,62], isoflavones [63,64], cinnamyl alcohols and cinnamic acids [65,66], anthocyanins [67,68] and ascorbic acid [69,70],... 

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. 

A Pd-MOF reported by Corma [60] was also found to be active in the partial oxidation of alcohols using air to oxidize 3-phenyl-2-propen-l-ol (cinnamyl alcohol). Ciimamyl alcohol is a suitable substrate to probe the activity and chemoselectivity of a catalyst for the aerobic alcohol oxidation. With Pd-MOF as catalyst and ambient pressure air as the oxidant, total conversion of ciimamyl alcohol was observed after... 

Typical substrates oxidized are p-nitro- and p-methoxybenzyl alcohol, geraniol, myrtenol, 2-cyclohexenol, cinnamyl alcohol, piperonyl alcohol and -hex-2-en-l-ol [32]. 

In another case, irradiation of a solution of the potential ODPM substrate trimethylbicyclo[2.2.2]octadienone 49 in acetone containing acetophenone only resulted in a cycloreversion process leading to toluene (90%) and dimethylketene. The ketene could be trapped by added cinnamyl alcohol to give ester 50 (90%). ... 

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