Glyoxalic acid, esters methyl ester

Glyoxal-sodium bisulfite, 30, 86 GlYOXYLIC acid, n-BUTYL ESTER, 35, 18 ETHYL ESTER, DIETHYL ACETAL, 35, 59 Grignard reaction, addition to ethyl sec-butylidenecyanoacetate, 35, 7 allylmagnesium bromide with o , 8-di-bromoethyl ethyl ether, 36, 61 allylmagnesium chloride with a,/3-di-bromoethyl ethyl ether, 36, 63 ethylmagnesium bromide with tin tetrachloride, 36, 86 N-methyl-l,2-diphenylethylamine,... 

Methyl glyoxylate and ( )-3-hexenol produce the acctoxyalkoxyacetic acid ester 4 in a two-step sequence. Cyclization of the glyoxal derivative 4 in the presence of tin(IV) chloride gave the tetrahydropyranylcarboxylate 5 in 83% yield after 6-endo reaction and chloride ion attack27. Tetrahydropyran 5 shows defined relative stereochemistry at all three asymmetric carbon centers. 

More than 15 preparations described in patents are variations of the above synthetic schane. hi particular, to obtain optically pure Emtricitabine, lipase-catalyzed enzymatic resolution, as well as chiral stationary phase HPLC was used [143]. However, the most effective procedure included separation of menthyl derivatives. This method evolved significantly since the first publication (which in fact relied on separation of all the 4 possible diastereomers) [144] one of the recent multigram preparations is shown in the Scheme 37 [145]. The first step of the synthesis included formation of methyl ester 159 from glyoxalic acid and L-menthol. Reaction of 159 with 1,4-ditiane 154 gave 1,3-oxathiolane 160 as a mixture of cis diastereomers. 

Glycothioses, I, 135 Glycuronide, III, 131 Glyoxal, methyl-, phytochemical reduction of, IV, 80 —, methyl-, III, 127 phenylosazone, III, 117, 122 Glyoxylic acid, ethyl ester, II, 89 IV, 128 Goepp, Rudolf Maximilian, Jr., obituary, III, xv-xxiii... 

The carbonyl ene reaction is between a similarly reactive aldehyde and an alkene rather than aketene. Glyoxalate esters and chloral are typical of the carbonyl compounds involved. Asymmetric versions rely on Lewis acid catalysts similar to those used in Diels-Alder reactions based on Ti and A1 among other metals.43 A simple example is the formation of 190 from methyl glyoxalate and an alkene 189 catalysed by 0.5mol% of a BINOL-Ti complex 191. Other alkenes that react well are 192 -195. 

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