Convert methylpropionate to propanal
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mp
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Explanation:
11 Translocation of Oxygen with Carbon and Aza Analogs
Analogs with a translocated atom of the ether linkage by a carbon atom have been also prepared. Thus, reaction of 2-amino-2-cyanoacetamide hydrochloride 516 with N,N-dimethyl-N′-benzyloxymethanimidamide 515 in methanol gave 517 as an unstable intermediate. Cyclization of 517 with the Lewis acid diethylether–boron trifluoride in 1,2-dimethoxyethane followed by catalytic hydrogenolysis over 10% palladium on charcoal afforded 518, isolated as its hydrochloride. Its alkylation with the 5-iodomethyl-2,2-dimethyl-1,3-dioxane, in the presence of potassium carbonate, gave the 1-alkoxyimidazole. A similar yield was obtained by using the mesylate and catalytic amounts of lithium iodide. Deprotection under acidic conditions gave the imidazol-1-yloxyalcohols 521 (90S893).
Alternatively, the construction of these nucleosides was achieved from the alkoxyamine derivative 520 by conversion to the respective formamidine 519. Transamidination followed by boron-trifluoride-catalyzed cyclization gave the imidazoles 522. Their cyclization was effected using sodium methylxanthate to give the purine thiolates, which upon oxidation with MCPBA gave the sulfonate, which directly reacted with hydroxylamine. Deprotection gave 523 [89JCS(P1)2207].
The alkoxyamine 524 was converted to the urea derivative 525, whose cyclization with 3,3-dimethyloxypropionate or ethyl-3,3-diethoxy-2-methyl-propionate was effected to give the pyrimidine derivatives 526. Their catalytic hydrogenation gave 527 (88TL4013). The cytosine derivative 529 was prepared via the triazolo derivatives 528, which upon aminolysis and deprotection gave 529. None of these compounds had significant antiviral activity.
