Bromodeoxy lactones

When the bromodeoxy lactones were boiled in water tetrahydrofurans were formed, whereas catalytic hydrogenation caused deoxygenation at C-2 and/or at the primary position, while the acetylated aldonolactones could also be reduced to 3-deoxylactones after elimination and stereospecific reduction. Substitution by azide introduced nitrogen functions at C-2 or at both bromo-substituted carbons, and these compounds could be converted into the corresponding amino acids. The new molecules could furthermore be reduced to the corresponding aldoses or alditols. 

The use of bromodeoxy lactones as chiral building blocks for the stereoselective preparation of natural compounds was also explored. Thus, both (5)-and (J )-carnitine, (S)- and (J )-4-amino-3-hydroxybutanoic acid (GABOB), compounds of high relevance for the central nervous system, as well as musc-aridine and 6-deoxyascorbic acid, were prepared by simple transformations of the bromodeoxy aldonolactones. 

From Bromodeoxy/Tosyloxy Aldonolactones to Other Lactone Synthons... 

At this point a comment is required about the formation of the 2,3-epoxy-o-mannonolactone 18 from the bromodeoxy-D-mannono-1,4-lactone 17 that has the bromine and the hydroxy groups in a cis relationship (Scheme 9). Obviously, a trans relationship between the bromine and the hydroxy group is necessary to form the epoxide within a five-membered ring. 

D-Glvcero-D-gulo-heptono-1.4-lactone and its penta-Q-acetyl derivative have been converted into deo - and bromodeoxy derivatives as indicated in Scheme 3. A study has been made of the complex reactions undergone by (8),(9) and (10) with aqueous base initally an epoxide is formed from each substrate, and subsequent reactions depend on the base strength, ib The a-azidolactones (11)-(13) are formed as isomerie mixtures by azide displacements applied to a-bromolactones. and in the case of compound (11) the seune mixture of epimers is produced from either of the epimeric bromo-precursors. Isomers (12) and (13) both gave the D-threo- product (14) on hydrogenation and acetylation n the use of products (12) and (13) for aminopentose synthesis is discussed in Chapter 9. 

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