Functionalized chiral diazaphospholanes ligate to a variety of transition metals, yielding chiral, catalytically active, metal complexes. Previous work has established that amino acid derivatization of the carboxyl groups of (R,R)-N,N'-phthaloyl-2,3-(2-carboxyphenyl)-phenyl-3,4-diazaphospholane (1) yields phosphines that are excellent ligands for palladium-catalyzed asymmetric allylic alkylatio...

The first highly diastereo- and enantioselective propargylic alkylation of acyclic ketone enamines to form vicinal tertiary stereocenters has been reported by employing copper catalysis in combination with a bulky and structurally rigid tridentate ketimine P,N,N-ligand.

In biogenesis of membrane proteins on the endoplasmic reticulum, a protein-conducting channel called the translocon functions in both the membrane translocation of lumenal domains and the integration of transmembrane segments. Here we analyzed the environments of polypeptide chains during the processes by water-dependent alkylation of N-ethylmaleimide at site-directed Cys residues. Using the te...

Catalytic asymmetric syntheses of various isoxazoline-N-oxides have been accomplished by asymmetric phase-transfer conjugate addition of bromomalonate to nitroolefins and subsequent ring-closing O-alkylation.

Mitomycin C (MC) activation to a reactive species was studied in nuclei isolated from rat liver and EMT6 tumor cells. Both preparations were similar in the rate of 4-(p-nitrobenzyl)pyridine (NBP) alkylation by MC and the levels of NADPH-cytochrome P-450 reductase. MC activation by both hepatic and EMT6 cell nuclei was inhibited by the presence of O2 and by heat inactivation. NADPH was preferred...

S(N)1-type alkylating agents, like N-methyl-N-nitrosourea (MNU) and N-ethyl-N-nitrosourea (ENU), are potent mutagens. Exposure to alkylating agents gives rise to O(6)-alkylguanine, a modified base that is recognized by DNA mismatch repair (MMR) proteins but is not repairable, resulting in replication fork stalling and cell death. We used a somatic mutation detection assay to study the in vivo e...

The transient dialkyl complexes [TaCp*R2(NAr)] (Cp*=C5Me5; R=Et, n-Pr; Ar=2,6-Me2C6H3), obtained by alkylation of [TaCp*Cl2(NAr)] with two equiv. of RMgCl in diethylether at low temperature, react with one equiv. of PMe3 to give [TaCp*(NAr)(CH2 CHR)(PMe3)] (R=H1, Me2) after b-elimination and reductive elimination of alkane. When the same alkylation is carried out and then one equiv. of CN(2,6-M...

The alkylation of phosphates in DNA by therapeutically active haloethylnitrosoureas was studied by reacting N-chloroethyl-N-nitrosourea (CNU) with dTpdT, separating the products by HPLC, and identifying them by co-chromatography with authentic markers. Both hydroxyethyl and chloroethyl phosphotriesters of dTpdT were identified; a similar reaction between CNU and dTR yielded 3-hydroxyethyl and 3...