Diethylene orthocarbonate

Diethylene orthocarbonate, C(—0CH2CH20- )2/Ts0H or wet BF3 Et20, CHCI3, 20° 70-9STo yield. ... 

Unlike the model system, (66) could not be brominated directly. Therefore, it was converted into the ketone (67) by heating in 80% acetic acid, and this ketone was brominated with excess bromine in ether to give (68). Conversion of (68) into the acetal (69) was accomplished with diethylene orthocarbonate and toluene-p-sulphonic acid. Rearrangement of (69) to (70) was effected by heating with excess 1,5-diazabicyclo[3,4,0]nonene in xylene-DMSO. On comparison of i.r., n.m.r., and mass spectral data, this synthetic racemate was identical with the corresponding derivative from natural chasmanine. 

When tetraphenyl orthocarbonate reacts with low terminal carboxyl PET, a small amount of diethylene glycol is formed by Side Reactions 27 and 28. 

Acetophenone is converted in this way into the diethylene ketal in 74% yield. Under the same conditions benzophenone is unreactive. The reagent appears particularly useful for preparation of acetals of aromatic ortho-hydroxy aldehydes. Ketalization of A -3-keto steroids is accompanied by migration of the double bond [(1) (2)]. The tetrathio orthocarbonate (3) can be used in the... 

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