Methoxymethyl Ether MOM Protection

Easily prepared and removed under mild acidic conditions, the methoxymethyl ether (MOM) protecting group has been widely utilized with a variety of tartrate derivatives. Treatment of diethyl tartrate (lb) with excess chloromethyl methyl ether in the presence of 7V, -diiso-propylethylamine furnishes in 79% yield diethyl 2,3-0-bis(methoxymethyl)-L-tartrate (623). This reaction is easily performed on a scale greater than 100 g [199,200]. 

Anisomycin (572), an antibiotic isolated from fermentation broth filtrates of various species of Streptomyces, possesses strong and selective activities against pathogenic protozoa and 

The intramolecular Michael reaction is useful for the preparation of nitrogen-containing heterocycles. Crucial to the success of this Michael reaction is the accessibility of substrates and nucleophilicity on the part of the nitrogen atom. The ability to control 1,2-asymmetric induction during formation of the heteroring is realized when the substrates are derived form tartaric acid derivatives. 

The diastereoselective hydride addition of a chiral metal hydride reagent to a ketone substrate bearing a stereogenic center is called a substrate-controlled process, and it leads to 1,2-asymmetric induction. Enantioselective hydride addition to a prochiral ketone by metal 

When first isolated from extracts from the skin of the Columbian poison frog Dendrohates histrionicus as a new alkaloid component, indolizidine 195B s (654) absolute stereochemistry needed to be established. Consequently, both enantiomers were synthesized. 

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Reductive cycHzations have been shown to be diastereoselective in the synthesis of bicyclic products as well as various macrocycles. There are also instances of chirahty transfer in intermolecular reductive couphngs. The synthesis of anti-1,2-diols has been demonstrated using a-alkoxyaldehydes with a methoxymethyl ether (MOM) protecting group and mono-aryl internal alkynes (Scheme 8.25) [49]. Dias-tereoselectivities are high for the formation of anfi-l,2-diols in cases where the aldehyde has a branched sp -P-carbon. 

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