Erythro ethyl 3-hydroxy-

Chemical Name erythro-p-hydroxy-a-[1-[(p-hydroxyphenethyl)amino] ethyl] benzyl alcohol... 

A catalytic enantioselective aldol-type reaction of ketene silyl acetals with achiral aldehydes also proceeds smoothly with 3a, which can furnish erythro p-hydroxy esters with high optical purities (Equation 42) [42b, c]. A remarkable finding is the sensitivity of this reaction to the substituents of the starting silyl ketene acetals. The reactions of silyl ketene acetals derived from more common ethyl esters are totally stereorandom, and give a mixture of syn and anti isomers in even ratios with improved chemical yields. In sharp contrast, the use of silyl ketene acetals generated from phenyl esters leads to good diastereo- and enantioselectivities with excellent... 

In ethyl 3-keto-2-oximino-3-phenylpropanoate catalytic hydrogenation over palladium on carbon reduced both the keto and oximino group, giving a 74% yield of ethyl ester of -phenylserine (ethyl 2-amino-3-hydroxy-3-phenylpropionate). The reduction is stereospecific and only the erythro dia-stereomer was obtained, probably via a cyclic intermediate 11097]. Similarly, hydrogenation over Raney nickel at 25-30° and 1-3 atm converted ethyl a-oximimoacetoacetate quantitatively to ethyl 2-amino-3-hydroxybutanoate [45]. 

METHOXYCARBONYL-1,1,6-TRIMETHYL-1,4,4a,5,6,7,8,8a-OCTAHYDRO-2,3-BENZOPYRONE, an intramolecular Diels-Alder reaction is responsible for the diastereoselectivity. The stereoselective 1,4-functionalization of 1,3-dienes is exemplified by a two-step process leading to cis- and trans-1-ACETOXY-4-(DICARBOMETHOXYMETHYL)-2-CYCLOHEXENE. The effectiveness of a silyl hydride in providing a means for erythro-directed reduction of a p-keto amide is applied in a route to ERYTHRO-1 -(3-HYDROXY-2-METHYL-3-PHENYL-PROPANOYLJPIPERIDINE. This is followed by an asymmetric synthesis based on a chiral bicyclic lactam leading to (R)-4-ETHYL-4-ALLYL-2-CYCLOHEXEN-1-ONE. The stereoselectivity with which acetoxy migration can operate to an adjacent radical center is reflected in the one-step reaction that gives rise to 1,3,4,6-TETRA-O-ACETYL-2-DEOXY-a-D-GLUCOPYRANOSE. 

R)-(-)-2,4-0-ETHYLIDENE-D-ERYTHR0SE AND ETHYL (E)-(-)-4,6-0-ETHYLIDENE-(4S,5R,1 R)-4,5,6-TRtHYDROXY-2-HEXENOATE (1,3-Dioxane-(R)-4-carboxaldehyde, 5-hydroxy-2-methyl-, [2R-(2a,4a,5p)]- and D-erythro-Hex-2-enonlc acid, 2,3-dideoxy-4,6-0-ethylidene-, ethyl ester [2E,4(S)]-)... 

P(R),5 -anhydro-2 3 -Q-isopropylideneadenosine-8-phosphonate hemi(ethyl acetate) solvate, 6,1 -anhydro-6-hydroxy-l-(2- -D-psicofuranosyl)cytosine (25) and the analogous 8,1 -anhydro-8-hydroxy-9-(2- -D-psicofuranosyl) adenine, 3 -amino-2 ,3 -dideoxythymidine hydrochloride, 3 -azldo-2, 3 -dideoxy-l- -D-erythro- and threo-pentofuranosyluracil. 2,4,6-trichloro- and 4-amino-6-chloro-8-... 

A soln. of cw-9,10-epoxystearic acid in benzene added dropwise with stirring during 10 min. to a soln. of 2,4,6-trinitrobenzenesulfonic acid in anhydrous dimethyl sulfoxide, stirring continued 15 min., stirred into excess cold ether-ethyl acetate (2 1), the solvent layer decanted, and the oily lower layer stirred 12-14 hrs. with water /hreo-9,10-dihydroxystearic acid. Y 65-70%. Also erythro- from trans-isomer, and prepn. of f. l-hydroxy-2-(alkoxysulfonium) salts, s. M. A. Khud-dus and D. Swern, Tetrah. Let. 1971, 411. 

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