Oxygen linkage

In seeking a synthetic route to an antibiotic antitumor agent, the Thiele-Winter synthon, with 2,3-bis(methoxycarbonyl)-l,4-ben2oquinone [77220-15-6] (60), was used to introduce a required third oxygen linkage (57). A 67% yield of (61) was obtained. 

Esterification. Esters are formed by the reaction of ethanol with inorganic and organic acids, acid anhydrides, and acid halides. If the inorganic acid is oxygenated, eg, sulfuric acid, nitric acid, the ester has a carbon—oxygen linkage that is easily hydrolyzed (24—26). 

The nature of the sulfur-oxygen bonds in sulfoxides and sulfones has been much discussed over many years. One would expect the actual structures to be intermediate between the canonical structures 3 and 6, and 8-11, respectively, and that discussion would be about the relative contributions of the various canonical structures. In practice the emphasis has been on the extremes is the sulfur-oxygen linkage in sulfoxides and sulfones essentially a coordinate bond or a double bond Various lines of evidence have been considered to bear on this question and these will now be examined briefly6. 

Scheme 3 Anchoring reaction of chromate on a silica support. Adjacent surface hydroxyl groups are consumed and chromiimi attaches to the siuface by oxygen linkages, either in mono-, di- or polychromate forms...

Our Form II has two uncommon features. In the first place it contains two hydroxyl groups attached to the same carbon but we have that in chloral hydrate. In the second place there is an ethylene oxide oxygen linkage. This might be called an alpha lactone with the water not split off. This formation of a ring structure is believed to account for the reversal of the sign of rotation. It is well known that the formation of the lactide from lactic acid, while not a lactone formation in the same... 

Network comprising only metal-oxygen linkages. 

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