Hiroyuki Nakamura

The reaction of allylstannanes 1 with aldehydes 2 in THF was catalyzed by Pd(II) or Pt(II) complexes (10 mol %) either at room temperature or at reflux, giving the corresponding homoallylic alcohols 3 in high to good yields. Among the catalysts examined, PtCl2(PPh3)2 gave the best result. No only allyltribitylstannane but also methallyl- and crotyltributylstannane could be utilized in this transition metal catalyzed reaction. Detailed mechanistic studies of the Pd(II)-catalyzed allylation, using

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCatalytic Asymmetric Allylation of Imines via Chiral Bis-π-allylpalladium ComplexesHiroyuki Nakamura, Kaori Nakamura, and Yoshinori YamamotoView Author Information Department of Chemistry, Graduate School of Science Tohoku University, Sendai 980-77, Japan Cite this: J. Am. Chem. Soc. 1998, 120, 17, 4242–4243Publication Date (Web):April 18, 1998Publication History Received9 October 1997Published online18 April 1998Published inissue 1 May 1998https

The use of the element boron, which is not generally observed in a living body, possesses a high potential for the discovery of new biological activity in pharmaceutical drug design. In this account, we describe our recent developments in boron-based drug design, including boronic acid containing protein tyrosine kinase inhibitors, proteasome inhibitors, and tubulin polymerization inhibitors, and ortho-carborane-containing proteasome activators, hypoxia-inducible factor 1 inhibitors, and topoiso

The reaction of certain activated alkenes 3 with allyltributylstannane (4) and allyl chloride (5a) in the presence of palladium catalyst gave the bis-allylation products, 1,7-octadiene derivatives 6a−k, in good to high yields. The reaction of certain imines 9 with 4 and 5a under similar conditions as above afforded the bis-allylated amines, N-allyl-N-3-butene-1-amine derivatives 10a−f, in good to high yields. The bis-allylation reactions most probably proceed through bis-π-allylpalladium interme

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAmphiphilic Catalytic Allylating Reagent, Bis-π-allylpalladium ComplexHiroyuki Nakamura, Jae-Goo Shim, and Yoshinori YamamotoView Author Information Department of Chemistry, Graduate School of Science Tohoku University, Sendai 980-77, Japan Cite this: J. Am. Chem. Soc. 1997, 119, 34, 8113–8114Publication Date (Web):August 27, 1997Publication History Received19 May 1997Published online27 August 1997Published inissue 1 August 1997https://pubs.acs.o

The mere presence or absence of PPh3 suffices to control the reactivity of bis(η3-allyl)palladium complexes. In the absence of PPh3 they undergo chemoselective allylic addition to aldehydes or imines, even in the presence of allylic chlorides, whereas in the presence of PPh3 the Stille coupling reaction takes place chemoselectively, even when aldehydes or imines are also present (see scheme).

Protein kinase C (PKC) is an important enzyme that helps govern cell metabolism and growth. The enzyme is physiologically activated when an (S)-diglyceride binds to its own regulatory domain. The saturable binding site of the regulatory domain can also be bound by any of a group of structurally diverse tumor promoters, including debromoaplysiatoxins (DATs), phorbol esters, ingenols, teleocidins, and bryostatins. The question of how the same binding site can be the target of these structurally di

Synthesis of allenes has been achieved by using palladium-catalyzed hydrogen-transfer reactions. Various propargylic amines, which were readily prepapred from iodobenzenes and propargylic amines by Sonogashira coupling reaction, underwent the hydrogen-transfer reaction in the presence of Pd2dba3.CHCl3/(C6F5)3P catalyst at 100 degrees C in dioxane for 24 h, giving the corresponding allenes in 43-99% yields. Various propargylic alcohols containing a propargylic aminomethyl group, synthesized by th

Abstract Dihydrofolate reductase from a methotrexate-resistant hamster cell culture was purified to apparent homogeneity by affinity chromatography. A similar procedure was used to prepare enzyme from wild type cells, although the final enzyme protein concentration was too small to be measured. The purified enzymes were not significantly different with regard to substrate specificity, Km values for folate and NADPH, sedimentation coefficient, electrophoretic mobilities at pH values 8.3 and 7.0,

The addition of o-carborane (1) to aldehydes 2 proceeded very smoothly in the presence of aqueous tetrabutylammonium fluoride (TBAF; 3 equiv) at room temperature, giving the corresponding carbinols 3 in high yields. The TBAF-mediated reaction was applied to the intramolecular cycloaddition of o-carboranyl aldehydes and ketones 4, and the corresponding five-, six-, and seven-membered carboracycles were obtained in good-to-high yields. Further, [3 + 2] annulation between o-carborane (dianionic C2

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTA Concise Synthesis of Enantiomerically Pure l-(4-Boronophenyl)alanine from l-TyrosineHiroyuki Nakamura, Masaru Fujiwara, and Yoshinori YamamotoView Author Information Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan Cite this: J. Org. Chem. 1998, 63, 21, 7529–7530Publication Date (Web):September 19, 1998Publication History Received30 April 1998Published online19 September 1998Published inissue 1 October 1998h

closo-Dodecaborate-encapsulating liposomes were developed as boron delivery vehicles for neutron capture therapy. The use of spermidinium as a counter cation of closo-dodecaborates was essential not only for the preparation of high boron content liposome solutions but also for efficient boron delivery to tumors.