The c-kit proto-oncogene encodes a receptor tyrosine kinase that is thought to play an important role in hematopoiesis. In a series of human acute myeloblastic leukemia (AML), the expression of the c-kit proto-oncogene and its product was studied by means of Northern blot and immunoblot analyses. The c-kit mRNA was expressed in 20 of 25 cases of AML, and in those cases the product of the c-kit proto-oncogene was detected by immunoblotting with anti-c-kit antibody. The expression of c-kit transcripts and protein was barely detectable in normal bone marrow cells as a control. The expression of c-kit transcript did not correlate with the French-American-British classification nor clinical manifestations. In 6 of 11 cases that expressed c-kit product, AML cells were found to proliferate in response to recombinant human stem cell factor (rhSCF), the ligand for c-kit, and the synergistic stimulation of AML cells was observed by rhSCF and granulocyte- macrophage colony-stimulating factor. Immunoblotting with anti- phosphotyrosine antibody showed that the c-kit receptor protein was detectably phosphorylated in 7 of 12 cases tested before the stimulation with rhSCF, while the rhSCF treatment resulted in an increased tyrosine phosphorylation of c-kit in AML cells. These results indicate that c-kit proto-oncogene is expressed in most cases of AML and is functional in terms of supporting proliferation.

Catalytic asymmetric alkynylation of carbonyl compounds is one of the most efficient routes for the synthesis of optically active propargylic alcohols, which are useful and versatile building blocks for a variety of functionalized molecules, such as biologically active natural products.[1] In the initial stages of development of this transformation, stoichiometric amounts of metal reagents such as organolithium, organomagnesium, and diorganozinc compounds were used to increase the nucleophilicity of the alkyne and to prevent an undesired retro reaction. [1,2] In terms of atom economy, [3] however, the direct in situ generation of a metal alkynylide species from terminal alkynes using a catalytic amount of the metal reagent is highly desirable. Since the pioneering work by Carreira and co-workers, who utilized catalytic amounts of Zn(OTf) 2 , Nmethylephedrine, and Et 3 N, [4] several efficient methods for the catalytic asymmetric alkynylation of aldehydes have been developed using chiral Zn, [5] In, [6] Cu, [7] and Ru [8] catalysts.[9]In contrast to the substantial progress made with aldehydes, the development of a catalytic asymmetric alkynylation of ketones for the construction of a tetrasubstituted carbon center in an enantioselective manner has had limited success due to low reactivity, difficulty in obtaining enantiofacial differentiation, and the ease of the retro reaction as compared with aldehydes.[10] Jiang et al. succeeded in promoting the asymmetric alkynylation of a-ketoesters with broad substrate scope and high enantioselectivity (up to 94 % ee)[11a] by modifying Carreiras Zn system. [4] Later, Shibasaki and co-workers reported Cu catalysis of trifluoromethyl ketone with up to 52 % ee, [11b] and the Rh catalysis of an a-diketone reported by Chisholm and co-workers gave the product in 5 % yield with 20 % ee.[11c] Although the method of Jiang et al. is useful for accessing chiral propargylic alcohols, there remains much room for improvement because this system requires 20 mol % catalyst loading, 30 mol % of external amine base, and a rather high reaction temperature (70 8C).[11a] Herein, we report the catalytic asymmetric alkynylation of a-ketoester 1 using various aryl-and alkylsubstituted terminal alkynes 2 catalyzed by as little as 3 mol % of C 1 -symmetric Rh/Phebox complexes 3 i and 3 j (Figure 1) to afford the corresponding propargylic alcohols with greater than 99 % ee. Because the acetate ligand on the Rh complex acted as an internal base, the reactions proceeded at 25 8C without any additives. An indanyl substituent on the oxazoline ligand was effective for obtaining high enantioselectivity and, in most cases, the C 1 -symmetric complex gave better results than the C 2 -symmetric complex. The electronic tuning of the Rh complex was achieved by introducing a nitro group at the para position to Rh and greatly improved both the reactivity and selectivity of the reaction. Moreover, the Rh complex had unique chemoselectivity; it selectively reacted with a a-ketoester over an aldehyde, thus allowing...

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Although the hydrogen reduction is thermally more disadvantageous than the CO reduction, it is advantageous that the reduction rate with H 2 is much larger than that with CO. In order to examine the effective use of hydrogen, the reduction of FeO 1.05 powder packed bed with H 2 -CO mixture was conducted, and the results were analyzed by a proposed model. The temperature, at which the reduction equilibria of FeO 1.05 with H 2 and CO equal, is determined to be 1 093 K from the present results. The apparent rate constants are determined to be 33, 8.6 and 15 for the reduction of FeO 1.05 with H 2 , CO and H 2 -CO mixture (V -H 2 : V -CO ϭ1 : 1), respectively. In the proposed model, when the water-gas shift reaction is taken into account, the additivity is established on the dependence of the rate constant of the reaction on the gas composition. When the water-gas shift reaction is not taken into account, the rate constant deviates negatively from the additivity. The apparent rate constants of the reduction determined in the present study take the middle values, and the contribution of the water-gas shift reaction is estimated to be 3 % against its equilibrium. In reducing FeO 1.05 with CO, the time when the sample is perfectly reduced is shortened by adding a small amount of H 2 , and the rate enhancement effect of H 2 on the gaseous reduction remarkably appears at 1 093 K. The effect originates in the proceeding of the water-gas shift reaction.

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