Alan S. Goldman

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During meiosis in Saccharomyces cerevisiae, DNA replication occurs 1. 5 to 2 hours before recombination initiates by DNA double-strand break formation. We show that replication and recombination initiation are directly linked. Blocking meiotic replication prevented double-strand break formation in a replication-checkpoint-independent manner, and delaying(More)
Meiotic recombination occurs more frequently in some regions of the eukaryotic genome than in others, with variations of several orders of magnitude observed in frequencies of meiotic exchange per unit physical distance. This article reviews what is known abut meiotic recombination hotspots loci, or regions that display a greater than average frequency of(More)
In Saccharomyces cerevisiae meiosis, recombination occurs frequently between sequences at the same location on homologs (allelic recombination) and can take place between dispersed homologous sequences (ectopic recombination). Ectopic recombination occurs less often than does allelic, especially when homologous sequences are on heterologous chromosomes. To(More)
To examine constrains imposed on meiotic recombination by homologue pairing, we measured the frequency of recombination between mutant alleles of the ARG4 gene contained in pBR322-based inserts. Inserts were located at identical loci on homologues (allelic recombination) or at different loci on either homologous or heterologous chromosomes (ectopic(More)
With petroleum supplies dwindling, there is increasing interest in selective methods for transforming other carbon feedstocks into hydrocarbons suitable for transportation fuel. We report the development of highly productive, well-defined, tandem catalytic systems for the metathesis of n-alkanes. Each system comprises one molecular catalyst (a(More)
s of Papers, 221st ACS National Meeting, San Diego, CA, April<lb>1-5, 2001; American Chemical Society:Washington, DC, 2001; INOR-<lb>287. (b) Dijkstra, H. P.; Slagt, M. Q.; McDonald, A.; Kruithof, C. A.; Kreiter, R.; Mills, A. M.; Lutz, M.; Spek, A. L.; Klopper, W.; van Klink, G. P. M.; van Koten, G. Eur. J. Inorg. Chem. 2003, 830. (c) Mehendale,<lb>N. C.;(More)
The insertion of an iridium complex into an N-H bond in ammonia leads to a stable monomeric amido hydride complex in solution at room temperature. This reaction advances the transition-metal coordination chemistry of ammonia beyond its role for more than a century as an ancillary ligand. The precursor for this insertion reaction is an iridium(I) olefin(More)
The pincer-ligated species (PCP)Ir (PCP = kappa3-C6H3-2,6-(CH2PtBu2)2) is found to promote dimerization of phenylacetylene to give the enyne complex (PCP)Ir(trans-1,4-phenyl-but-3-ene-1-yne). The mechanism of this reaction is found to proceed through three steps: (i) addition of the alkynyl C-H bond to iridium, (ii) insertion of a second phenylacetylene(More)
The iridium pincer complexes (PCP)IrH(4) (1; PCP = [kappa(3)-1,3-(CH(2)P(t)Bu(2))(2)C(6)H(3)]) and (POCOP)IrH(4) (2; POCOP = [kappa(3)-1,3-(OP(t)Bu(2))(2)C(6)H(3)]) have proven to be effective catalyst precursors for dehydrogenation of alkanes. The complex (POCOP)IrH(2) has also been applied successfully as a catalyst for release of H(2) from ammonia(More)
The reactions of aryl and alkylamines with the (PCP)Ir fragment (PCP = 1,3-di-tert-butylphosphinobenzene) were studied to determine the reactivities and stabilities of amine and amido hydride complexes relative to C-H activation products. Reaction of aniline with the (PCP)Ir unit generated from (PCP)IrH2 and norbornene resulted in the N-H oxidative addition(More)