1- phenylpropane-l,2-diol

Phenylpropane-l,2-diols, A21.1, A21.2, A"16 Spiro[4.4]nonane-l, 6-dione, X 3.9 Norbornenecarboxylic acids, methyl esters,... 

Phomopsis sp. strain endophytes of the medicinal plant Erythrina crista-galli continue to yield novel compounds (Table 1). New phenyl-propane, pyronol, benzoic acid, phenylpyran, macrocyclic, and alkene compounds were discovered, as well as the known compounds clavatol, 4-hydroxymellein, mellein, mevalonolactone, mevinic acid, nectriapyrone, phomol, scytalone, and tyrosol. The new compounds were phomopy-ronol (101), 3-phenylpropane-l,2-diol (102), 4-(2,3-dihydroxypropoxy) benzoic acid (103), 2-(hydroxymethyl)-3-propylphenol (104), 2-... 

Fig. 10. Oxidation of fAteo-l-phenylpropane-l,2-diol by periodate. 1M acetate buffer pH 4.7. 1 X 10 5 periodate, 1 x 10diol, 25° C. Time (in minutes) after which the recording of each curve was started is noted. Curves starting at 0 V, 200 mV/absc., 450 mV/min., mercurous sulphate reference electrode, h = 50 cm, full scale sensitivity 0.6 [ A...

With diamine (25), 1-heptene afforded (/ )- ,2-heptanediol as the major ixoduct (86% ee) in 75% yield by this procedure but, curiously, oxidation of ( )-stilbene proceeded with lower optical yield (34% ee). Particularly efficient enantioface differentiation was achieved in the reaction of ( )-l-phe-nylpropene with a stoichiometric amount of osmium tetroxide in the presence of 1 mol equiv. of (-)-(27) when essentially optical pure (>99% ee) (15,2S)-l-phenylpropane-l,2-diol was obtained in 73% yield. This procedure is effective for mono-, ( )-di- and tri-substituted alkenes, with enantioface selection being as shown in Scheme 2 but, notably, the oxidation of (Z)-alkenes does not give satisfactory optical yields. 

Fig. 45. Oxidation of tAreo-l-phenylpropane-l,2-diol by periodate. 1 M Acetate buffer pH 4-7, 1x10 M l-phenylpropane-l,2-diol, 25 °C. The curves were recorded after elapsing of the time marked on the beginning of the curve on polarogram, starting at 0-0 V, mercurous sulphate electrode, 200 mV/absc., 325 mV/min, tj = 2-8 sec m — V9 mg/sec, full scale sensitivity 3-2/lA.

If , if , 4 )- (lf , 3S, 4 )-4-Acetoxy-3-3-hydroxy-2-oxocyclochexyl acetate (1,2,4)-4-Acetyl-1 -methylcyclohexane-1,2-diol 3-Azido-2-hydroxy-l-phenylpropan-l-one -t3-Azido-2-hydroxy-l-phenylpropan-2-one... 

Scheme 3.1.1 Enantio- and diastereoselective enzymatic synthesis of l-phenylpropane-1, 2-diol stereoisomers in a reaction sequence. recLbADH, recombinant ADH from Lactobacillus brevis Th.sp.-ADH, ADH from Thermoanaerobium species. After crystallization ee > 99%.

Thus, when 2,2-dimethyl-, 2-methyl-2-n-propyl- and 2-methyl-2-iso-amylpropane-l,3-diol were treated with diethyl carbonate in the presence of catalytic amounts of sodium methoxide, only PCs were produced in high yield. On the other hand, six-membered cyclic carbonates are exclusively produced when 2,2-diethyl-, 2-ethyl-2-phenylpropane-1,3-diol, pentane-2,4-diol, 2-methylpentane-2,4-diol, and butane-1,3-diol were subjected to the transesterification reaction (Scheme 10). 

This whole-cell biotransformation is still a subject of research for several reasons Besides fhe desired product (1 )-PAC, several by-products are formed through enzymatic reduction of fhe product or fhe substrate benzaldehyde, resulting in the formation of l-phenylpropan-2,3-diol and benzylalcohol, respectively. Further byproducts are acetoin, butane-2,3-dione, l-phenyl-propane-2,3-dione, benzoic acid and 2-hydroxypropiophenone, leading to a reduced yield of the desired product and difficult product isolation. To circumvent fhis problem strain improvement and reaction engineering have been used [15, 16]. Application of an isolated enzyme in a two-phase system resulted in improved space-time yield and high product purity [17]. 

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