Ring−Chain Tautomerism of the Novel 2-Ferrocenyl-2,4-dihydro-1H-3,1-benzoxazine

A novel type of organometallic 2-R-2,4-dihydro-1H-3,1-benzoxazine with R = [M(η5-C5H4)(CO)3] (M = Re or Mn) units. Experimental and computational studies of the effect of substituent R on ring-chain tautomerism

Novel 2-cyrhetrenyl and cymantrenyl-2,4-dihydro-1H-3,1-benzoxazines.

Solvent-catalyzed ring-chain-ring tautomerization in axially chiral compounds

The mechanism of ring-chain-ring tautomerization and the prominent effect of the solvent environment have been computationally investigated in an effort to explain the enantiomeric interconversion observed in 2-oxazolidinone derivatives, heterocyclic analogues of biphenyl atropisomers, which were isolated as single stable enantiomers and have the potential to be used as axially chiral catalysts. This study has shed light on the identity of the intermediate species involved in the ring-chain-ring tautomerization process as well as the catalytic effect of polar protic solvents. These mechanistic details will prove very useful in predicting and understanding ring-chain tautomeric equilibria in similar heterocyclic systems and will further enable experimentalists to devise appropriate experimental conditions in which axially chiral catalysts remain stable as single enantiomers.

3,4-Dihydro-1H-[1,3]oxazino[4,5-c]acridines as a new family of cytotoxic drugs

A series of [1,3]oxazino fused acridines has been prepared as precursors of cytotoxic 3-amino-4-hydroxymethylacridine 2. Their cytotoxic activity has been evaluated against HT29 colon carcinoma cell line and was shown to be dependent on the nature of the substituent located on position 2 of the oxazine ring. Additionally, the nitrophenyl derivative 3f is activated by nitroreductase, indicating its potency as prodrug for either gene-directed or antibody-directed enzyme prodrug therapies.