Synthesis of Novel Trispiroheterocycles through 1,3-Dipolar Cycloaddition of Azomethine Ylides and Nitrile Oxide

Synthesis of Octahydropyrano[2,3-d]Pyrimidine Derivatives via Tetrahydropyrano[3,2-e][1,3]Thiazolo[3,2-a]Pyrimidine and 2,6-Dichlorobenzonitrile Oxide

N1-substituted octahydro-1 H-pyrano[2,3- d]pyrimidines derivatives were prepared in moderate yield by the reaction of methyl [(4a RS,5 SR,10a RS)-5-aryl-2-oxo-3,4,4 a,10 a-tetrahydro-2 H,5 H-pyrano[3,2- e][1,3]thiazolo[3,2- a]pyrimidin-8(9 H)-ylidene]acetate and 2,6-dichorobenzonitrile oxide via a domino 1,3-dipolar cycloaddition/ring-opening/dethionation process. The structures of the products were characterised by spectroscopic and X-ray crystallographic analysis.

Spectroscopic studies on the interaction of BSA and 5-spiro-3'-piperidine-2″-spiro-3″-indole-4',2″-diones

The interaction of 5-spiro-3'-piperidine-2″-spiro-3″-indole-4',2″-diones (SPSDs), an anti-tumor drug, to bovine serum albumin (BSA) in aqueous solution has been investigated by fluorescence spectra and ultraviolet-visible (UV-vis) spectra at pH 7.40. We have studied the effect of four substituents on the SPSD for the first time. The results of fluorescence titration indicated that SPSD can quench the intrinsic fluorescence of BSA and the quenching mechanism has been analyzed. The binding sites number (n), the binding constant (K(A)) and the spatial-distance (r) of SPSD with BSA without or with substituents on the benzene ring at 302 and 310 K have been calculated. The results show that the presence of the substituents increased the binding constant and changed the binding distance between the acceptor and the donor, which possibly results from the formation of SPSD-BSA complex. We have investigated the possible sub-domain on BSA where bind SPSD by displacement experiments. The effect of SPSD on the conformation of BSA has also been analyzed using synchronous fluorescence under experimental conditions.