R -«-Phenylethylamine

The imine 83 derived from (R)-phenylethylamine adds to cyclopentadiene in the presence of trifluoroacetic acid and a catalytic amount of water to afford a 97 3 mixture... 

The best results observed so far were with the central- and planar-chiral ketimine ligands, all of which were synthesized with the same chiral amine, (S)- or (R)-phenylethylamine, to result in the same central-chiral side-chain. The second generation of these ligands was synthesized with the various chiral amines depicted in Fig. 2.1.3.5 based on the AHPC 2 and BHPC 3. 

Scheme 13.3 Racemization of (R)-phenylethylamine with base at high temperature.

As shown in Scheme 1.2.2, the synthesis starts from a chiral imine 4, which is prepared from ethylglyoxylate and (R)-phenylethylamine, by an aza-Diels-Alder reaction, leading to azabicyclooctene 5 in fair yield. This unsaturated precursor can be converted to pipecolic acid derivative 7 by ozonolysis and subsequent functional group transformations as depicted in Scheme 1.2.2. 

Reduction191 of the imine (367) with diborane followed by a catalytic hydrogenation produced 20a(20S)- and 20/3(20R)-amines, (370) and (371), in the ratio 55 45. Reduction employing (+ )-di-3-pinanylborane gave a similar mixture. However, when chirality was introduced into the imine as in (368) [prepared from (S)-phenylethylamine] diborane reduction yielded uniquely the 20a -amine (370) (funtuphyllamine A). The imine (369), prepared from ( + )-(R)-phenylethylamine, gave (370) (8%) and (371) (92%). 

Koshima, H., Matsushige, D. and Miyauchi, M. (2001) Enantiospecific single crystal-to-single crystal photocyclization of 2,5-diisopropyl-4 -carboxybenzophenone in the salt crystals with (S)- and (R)-phenylethylamine. Cryst.Eng.Comm., 33, 1-3. 

Free Sugars and Simple Derivatives Thereof.- The inclusion complex of (R)-phenylethylamine with 2,3.4,6-tetra-O-acetyl-D-glucose. ... 

Deamination, Transamination. Two kiads of deamination that have been observed are hydrolytic, eg, the conversion of L-tyrosiae to 4-hydroxyphenyUactic acid ia 90% yield (86), and oxidative (12,87,88), eg, isoguanine to xanthine and formycia A to formycia B. Transaminases have been developed as biocatalysts for the synthetic production of chiral amines and the resolution of racemic amines (89). The reaction possibiUties are illustrated for the stereospecific synthesis of (T)-a-phenylethylamine [98-84-0] (ee of 99%) (40) from (41) by an (5)-aminotransferase or by the resolution of the racemic amine (42) by an (R)-aminotransferase. 

In the same way, (+)- and (-)-lactic adds react with (ft)-l-phenylethylamine to give two different products (Figure 9.13). (-R)-Lactic acid reacts with... 

Twro diastereomeric salts (R)-lactic acid plus (5)-1-phenylethylamine and (S)-lactic acid plus (5)-l-phenylethylamine... 

Further reactions of allyl organometallics with a-alkoxyaldimines 1, prepared from (S)-2-(methoxymcthoxy)propionaldehyde and (R)- and (S)-l-phenylethylamine, illuminate the difference in the influence of the nitrogen chiral auxiliary and the x-alkoxy center7. 

Among the amines that have been resolved with (-)-DAG are a-phenylethylamine (a-methylbenzenemethanamine),s [R-(R, R )]-2-amino-l-(4-nitrophenyl)-l, 3-propanediol,61,2,3,4,5,6,7,8-octahydro-l-(4-methoxyphenylmethyl)isoquinoline, 3-methoxymorphinan, 1,2,3,4-tetrahydro-7-methoxy-4-phenylisoquinoline, 3-hydroxy-A7-methyl-... 

R) -A -(ethoxycarbonylmethyl)-l-phenylethylamine (C12H17NO2 66512-37-6) see Etomidate lV -ethoxycarbonyl-2-methylpiperazine (QH16N2O2 120737-73-7) see Temafloxacin 7a-ethoxycarbonylmethylpyrrolizlne (CjjHjyN02 88069-56-7) see Pilsicainide 6-ethoxycarbonyl-2-methylthio-5-oxo-5,8-dihydro-pyrldo[2,3-d]pyrimidine... 

By heating 2-benzyloxycyclohexanone 208 and (R)-l-phenylethylamine in refluxing toluene for 4 days in a Dean-Stark apparatus, the imine 209 was formed, then a rearrangement occurred to give first the a-aminocyclohexanone derivative 210 and finally the Q, o -disubstituted imine 211 with moderate diastereoselectivity. Reduction of this imine with sodium borohydride gave a mixture of two trans diamines (S,S)-212 and (R,R)-212, which were separated by chromatography. The enantiomers of 1-benzyl-1,2-diaminocyclohexanes 213 were then obtained by hydrogenolysis [99] (Scheme 31). 

This interpretation was supported by further investigations by GiacomelH and coworkers [73]. Racemic 4-phenyl-l-hexene was kineticaUy resolved by isomerization of the double bond using a catalyst system consisting of Al Buj, (R)-N,N-di-methyl-l-phenylethylamine and Ni(mesal)2. Very poor enantioselectivities (ee < 0.3%) were observed for both the isomerization product and the unreacted alkene. The authors note that it is essential to first react the alane with the chiral amine. No... 

CR)-Phenylethylamine-2-CR)-methyl-l-boraadamantane (R,R) 57 (92% de) was obtained in a similar manner using the opposite enantiomer of the resolving agent, (i )-(+)-phenylethylamine (Scheme 21) <2003MC121, B-2003MI97>. 

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