Oxazolones 3-Oxazolin-2-ones

Phenylmercuric chloride, conversion to phenyltrichloromethylmercury by reaction with sodium tri-chloroacetate, 46, 98 2-Phenyl-2-oxazolin-5-one, 47, 101 2-Phenyl-5-oxazolone, 47,101... 

Most of the reports, since the 1980s, on the chemistry of 2-oxazolones concern 2(3f/)-oxazolones (4-oxazolin-2-ones) 1 and only few reports have appeared on the isomeric 2(5//)-oxazolones (5-oxazolin-2-ones) 2. Thus, the emphasis of this chapter has been to survey information on the synthesis and reactions of the 2(3//)-oxazolones 1 that has appeared over the past two decades. 

The 5-oxazolones or oxazolin-5-ones are very interesting heterocyclic compounds that have been used as intermediates in the synthesis of a variety of organic molecules. Two structural classes are possible, the 5(27T)-oxazolones (or 3-oxazo-lin-5-ones) and 5(47T)-oxazolones (or 2-oxazolin-5-ones). These structures differ only in the position of the double bond. Apart from the presence of the heteroatoms (N and O), the carbonyl group and the double bond, the 2- or 4-position, respectively, can be saturated or unsaturated. The isomeric 5-oxazolones are... 

A samrated 5(2//)-oxazolone, also known as a 3-oxazolin-5-one or a pseudox-azolone, can be considered as the tautomer of a saturated 5(4//)-oxazolone (or 2-oxazohn-5-one) by a 1,3-prototropic shift (Scheme 7.1). 

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