Stereoselective Construction of Spiro-Fused Tricyclic Frameworks by Sequential Reaction of Enynes, Imines, and Diazoalkenes with Rh(I) and Rh(II) Catalysts.

Stereoselective construction of spiro-fused tricyclic compounds from enynes having a tethered imine with diazoalkenes was achieved by Rh(I)- and Rh(II)-catalyzed sequential reactions. This method consists of three reactions, i.e., Rh(I)-catalyzed cyclization of enynes with a tethered imine, Rh(II)-catalyzed cyclopropanation with diazoalkenes, and Cope rearrangement. Notably, the sequential reactions can be operated in one pot, in which Rh(I) and Rh(II) catalysts work in relay without any serious catalyst deactivation to afford the spirocycles in a stereoselective manner.

Indazole-based potent and cell-active Mps1 kinase inhibitors: rational design from pan-kinase inhibitor anthrapyrazolone (SP600125).

Monopolar spindle 1 (Mps1) is essential for centrosome duplication, the spindle assembly check point, and the maintenance of chromosomal instability. Mps1 is highly expressed in cancer cells, and its expression levels correlate with the histological grades of cancers. Thus, selective Mps1 inhibitors offer an attractive opportunity for the development of novel cancer therapies. To design novel Mps1 inhibitors, we utilized the pan-kinase inhibitor anthrapyrazolone (4, SP600125) and its crystal structure bound to JNK1. Our design efforts led to the identification of indazole-based lead 6 with an Mps1 IC50 value of 498 nM. Optimization of the 3- and 6-positions on the indazole core of 6 resulted in 23c with improved Mps1 activity (IC50 = 3.06 nM). Finally, application of structure-based design using the X-ray structure of 23d bound to Mps1 culminated in the discovery of 32a and 32b with improved potency for cellular Mps1 and A549 lung cancer cells. Moreover, 32a and 32b exhibited reasonable selectivities over 120 and 166 kinases, respectively.

Asymmetric 1,3-dipolar cycloadditions of N-benzyl and N-diphenylmethyl nitrones and alpha,beta-unsaturated aldehydes catalyzed by bis-titanium chiral Lewis acids.

Bis-titanium chiral Lewis acids that contain two oxygen-bridged titanium centers were successfully applied to the asymmetric 1,3-dipolar cycloaddition of nitrones and alpha,beta-unsaturated aldehydes. The introduction of the diphenylmethyl group as the N substituent on the nitrones, with the aim of destabilizing the nitrone-Lewis acid complex, led to the drastic enhancement of not only the reactivity but also the enantioselectivity. By employing this approach, 1,3-dipolar cycloadditions of nitrones and the rather unreactive methacrolein were facilitated to give cycloadducts that bear one all-carbon quaternary center with unique regioselectivity and excellent stereoselectivity.