Lithium, methoxyl methyl

Formyl-2-methylfuran was converted in 75% yield into derivative 319 by electrolytic methoxylation. A corresponding mixture of cis-diols (320) was treated with Dowex W-50 ion-exchange resin in methanol for four days, to afford 5-deoxy-3-C-(dimethoxymethyl)-DL-eryf/rro-4-pentulose dimethyl acetal (321). Reduction of this compound with lithium aluminum hydride or sodium borohydride gave a mixture of 5-deoxy-3-C-(dimethoxymethyl)pentoses, which was separated by column chromatography on silica gel, to give206 DL-streptose tetramethyl acetal (322) and the isomeric 5-deoxy-3-C-(dimethoxy-methyl)-DL-ribose dimethyl acetal 323 (hjxo ribo = 13 7). Detailed, combined gas-liquid chromatographic-mass spectrometric analysis of the compounds related to streptose (in the form of their trimethyl-silyl derivatives) has been described.207... 

The cis relationship between the phenyl and methoxyl groups in CLIX has been confirmed by recent synthetic studies of Uyeo and his co-workers (86). Dihydroisotazettinol (in which the 3-hydroxyl and the phenyl are trans) was oxidized by manganese dioxide to CLIXa. Treatment of CLIXa with lithium aluminum hydride and cyclization of the resultant triol with dilute sulfuric acid gave an ether (CLIXb), the methi-odide of which afforded the neutral compound CLIXc upon Emde reduction. The synthesis of CLIXc started with CLIXd, the condensation product of piperonyl cyanide and methyl acrylate. Dieckmann... 

Since in most naturai protOberberines C13 has no substituent, or at most a methyl or methoxyl group (Refs. 2, 17), it is of interest to be able to avoid the arylation of C13 observed in 21. Fortunately, this is achieved by the presence of a methyl group at the corresponding position in the pyrrolinedione, which has enabled us to carry out total synthesis of corydaline (22)- 3,4-dimethoxybenzyne (22d) reacts regioselectively with the pyrrolinedione 29b to give a 32% yield of the adduct 34a. which reduction with lithium aluminium hydride and sodium borohydride converts into corydaline (Scheme 11)(Ref. 16). 

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