Cyclic sulfate chemistry

A synthesis of (R)-reticuline included a comparison of epoxide and cyclic sulfate chemistry (Scheme 3.31) [345]. 

Dioxathiolane. Y-oxidcs (cyclic sulfites) and 1,3,2-dioxathiolane. Y,.Y-dioxides (cyclic sulfates) have been widely used in organic chemistry, mostly as the synthetic equivalents of epoxides (Sections 6.05.5 and 6.05.6 Tables 1-7). 

Heterocycles of this type occur widely. The benzo[l,3]dioxole ring system is often found in natural products and their degradation products, e.g., sesamol 38 lipoic acid 39 is a naturally occurring 1,2-dithiolane derivative. The 1,3-dithiolanes 40 are commonly known as 1,3-dithioacetals and have been extensively used in carbonyl group chemistry. In the absence of cyclic conjugation, ring sulfur atoms can readily exist in higher oxidation states as, for example, in the oxathiole S, -dioxide 41. 1,3,2-Dioxathiolane A-oxides 42 (cyclic sulfites) and 1,3,2-dioxathiolane A,A-dioxides (cyclic sulfates) are useful as synthetic equivalents of epoxides. 

The cinchona alkaloids have opened up the field of asymmetric oxidations of alkenes without the need for a functional group within the substrate to form a complex with the metal. Current methodology is limited to osmium-based oxidations. The power of the asymmetric dihydroxylation reaction is exemplified by the thousands (literally) of examples for the use of this reaction to establish stereogenic centers in target molecule synthesis. The usefulness of the AD reaction is augmented by the bountiful chemistry of cyclic sulfates and sulfites derived from the resultant 1,2-diols. 

The chemistry of cyclic sulfites and cyclic sulfates, although not new, has only recently begun to be explored by synthetic chemists. In recent years, several synthetic applications of cyclic sulfites and sulfates have appeared. In this chapter, attempts have been made to draw the attention of synthetic chemists to the great potential hidden in this neglected class of useful organic compounds, which at present is accessible in homochiral form via the recently discovered asymmetric dihydroxylation of alkenes. 

A review on the use of cyclic sulfites and cyclic sulfates as epoxide equivalents contained a number of applications to carbohydrate chemistry. ... 

Other intermediate-duration oral studies in rats evaluated effects of aluminum on brain chemistry as well as neurobehavioral performance. Rats that consumed 51 mg Al/kg/day as aluminum chloride in drinking water for 180 days had alterations in behavior (reduced spontaneous locomotor activity, impaired learning, extinction and relearning of an active avoidance task, impaired maze relearning ability) and brain chemistry (increased lipid peroxidation, decreased activity of Na+-, K+-, and Mg2+-ATPases) (Lai et al. 1993). Ingestion of 490 mg Al/kg/day as aluminum sulfate in drinking water for 4-12 weeks caused reduced retention of a learned passive avoidance task and changes in brain chemistry (e.g., increased cyclic adenosine monophosphate levels, decreased concentrations of MAP-2 and other structural... 

The typical S-oxidation with BVMOs allows the formation of chiral sulfoxides from organic sulfides. This oxidation has received much interest in organic chemistry due to its use in the synthesis of enantiomerically enriched materials as chiral auxiliaries or directly as biologically active ingredients. This reaction has been studied extensively with CHMO from Adnetohacter showing high enantioselectivi-ties in the sulfoxidation of alkyl aryl sulfides, disulfides, dialkyl sulfides, and cychc and acyclic 1,3-dithioacetals [90]. CHMO also catalyzes the enantioselective oxida-hon of organic cyclic sulfites to sulfates [91]. 

In another approach, commercially available ethyl fran.y-cinnamate was used as starting material, and similar chemistry to that described above was performed, except that the cyclic sulfite 7.2.16 was opened directly with azide instead of being oxidized to sulfate the resulting azidoalcohol 7.2.17 had the opposite stereochemistry at C-2. The stereochemistry at C-2 was inverted by the Mitsonobu procedure to give... 

This chapter will discuss methods for the preparation of esters, acid chlorides, anhydrides, and amides from carboxylic acids, based on acyl substitution reactions. Acyl substitution reactions of carboxylic acid derivatives will include hydrolysis, interconversion of one acid derivative into another, and reactions with strong nucleophiles such as organometallic reagents. In addition, the chemistry of dicarboxylic acid derivatives will be discussed, as well as cyclic esters, amides, and anhydrides. Sulfonic acid derivatives will be introduced as well as sulfate esters and phosphate esters. Finally, nitriles will be shown to be acid derivatives by virtue of their reactivity. 

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