2,4-Oxazolidinediones

Tautomerism of 2‐amino‐2‐oxazolin‐4‐ones. II

“…These results are in agreement with what is expected for conjugated 2-amine derivatives of a structure (l), at least in these solvents, but in this case also the weak intensity of the 1740 cm-' band must be noted. On the other hand, the frequency of this absorption is in agreement with what is to be expected for amido five-membered rings (14)(15)(16)(17)(18)(19)(20). Exceptions, however, can be noted: in isoxazolin-3-ones (21) and in 5-amino-isoxazolin-3-ones (22,23), the i; C=O i s assigned to bands between 1657 and 1667 cm-' , the lowering of the frequency being attributed to the contribution of the resonance form having separated charges on the endocyclic nitrogen and on the oxygen of the carbonyl group, However, in our case it was impossible to attribute the higher frequency bands to combination tones.…”

Mild deprotection of the N-tert-butyloxycarbonyl (N-Boc) group using oxalyl chloride

“…37,38 It has been shown that the oxazolidinedione scaffold undergoes hydrolysis and ring opening to release carbon dioxide and related products. 39,40 It is therefore plausible that aer the workup, the oxazolidinedione-like intermediate, 9 will undergo a ring opening and subsequently yield the amine product, 11, by releasing carbon dioxide, carbon monoxide and possible formyl side products. It must be noted that the tert butyl cation sideproduct produced from the conversion of 8 to 9, will be transformed into isobutanol.…”

Synthesis and structure-activity studies of a series of spirooxazolidine-2,4-diones: 4-oxa-analogs of the muscarinic agonist 2-ethyl-8-methyl-2,8-diazaspiro[4.5]decane-1,3-dione

“…Synthesis of oxazolidine-2,4-dione derivatives has been well studied. 23 Concerning the spirooxazolidine-2,4-diones, Nagai et al 24 have reported the preparation of 8-benzyl-l-oxa-3,8-diazaspiro [4.5]decane-2,4-dione derivatives. Their synthetic methods were applied to the synthesis of our target compounds.…”