Gregory T. Whiteker
Dow AgroSciences
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Gregory T. Whiteker.
ChemInform | 2012
Gregory T. Whiteker; Christopher J. Cobley
This review summarizes the known commercial applications of rhodium-catalyzed olefin hydroformylation to fine chemical synthesis. Two manufacturing processes for Vitamin A utilize hydroformylation. Additional, recent examples of hydroformylation on multikilogram scale for synthesis of pharmaceutical building blocks have also been reported. Hydroformylation appears to be widely used in the fragrance industry, where aldehydes are ubiquitous. Numerous fragrance ingredients are commercially prepared by hydroformylation. There are no reports of agrochemical manufacturing processes which employ hydroformylation. In addition to commercial applications, examples of pharmaceutical, fragrance, and agrochemical products which have been prepared on small scale using hydroformylation are given. Hydroformylation appears to be well suited to fine chemical synthesis, and applications should increase as process chemists become more aware of its potential.
Bioorganic & Medicinal Chemistry | 2016
Jeffrey Epp; Anita Lenora Alexander; Terry William Balko; Ann M. Buysse; William Kirkland Brewster; Kristy Bryan; John F. Daeuble; Stephen Craig Fields; Roger E. Gast; Renard Antonio Green; Nicholas Martin Irvine; William C. Lo; Christian T. Lowe; James M. Renga; John Sanders Richburg; James Ruiz; Norbert M. Satchivi; Paul R. Schmitzer; Thomas L. Siddall; Jeffery Webster; Monte R. Weimer; Gregory T. Whiteker; Carla N. Yerkes
Multiple classes of commercially important auxin herbicides have been discovered since the 1940s including the aryloxyacetates (2,4-D, MCPA, dichlorprop, mecoprop, triclopyr, and fluroxypyr), the benzoates (dicamba), the quinoline-2-carboxylates (quinclorac and quinmerac), the pyrimidine-4-carboxylates (aminocyclopyrachlor), and the pyridine-2-carboxylates (picloram, clopyralid, and aminopyralid). In the last 10 years, two novel pyridine-2-carboxylate (or picolinate) herbicides were discovered at Dow AgroSciences. This paper will describe the structure activity relationship study that led to the discovery of the 6-aryl-picolinate herbicides Arylex™ active (2005) and Rinskor™ active (2010). While Arylex was developed primarily for use in cereal crops and Rinskor is still in development primarily for use in rice crops, both herbicides will also be utilized in additional crops.
Pest Management Science | 2011
Jesse L. Balcer; Carl Deamicis; Peter L. Johnson; Jerzy Klosin; Gregory T. Whiteker; C Srinivas Rao; Donghua Dai
BACKGROUND Tricyclazole is a commercial fungicide used to control rice blast. As part of re-registration activities, samples of metabolites and process impurities are required. In addition, isotopically labeled tricyclazole samples are also required. RESULTS Four new compounds related to tricyclazole are reported. An isotopically labeled sample of tricyclazole was prepared that contained two (15)N atoms and one (13)C atom. Radiolabeled tricyclazole with (14)C at the triazole C3 position was also synthesized. A new process impurity in technical tricyclazole was identified and synthesized. A new metabolite of tricyclazole was identified, independently synthesized and characterized by X-ray crystallography. CONCLUSION A previously unreported metabolite of tricyclazole has been identified and structurally characterized. In addition, a new process impurity has been identified by independent synthesis. Identification of these new compounds has facilitated the continued registration of this important fungicide.
New Journal of Chemistry | 2017
Zhao Li; Carol Gelbaum; Zachary S. Campbell; Paul C. Gould; Jason S. Fisk; Bruce S. Holden; Arvind Jaganathan; Gregory T. Whiteker; Pamela Pollet; Charles L. Liotta
The Pd-catalyzed Suzuki coupling reactions of a series of aryl chlorides and aryl bromides containing basic nitrogen centers with arylboronic acids in water in the absence of added base are reported. The reactions proceed either partially or entirely under acidic conditions. After surveying twenty-two phosphorus ligands, high yields of products were obtained with aryl chlorides only when a bulky ligand, 2-(di-tert-butyl-phosphino)-1-phenyl-1H-pyrrole (cataCXium®PtB) was used. In contrast, aryl bromides produced high yields of products in the absence of both added base and added ligand. In order to explore the Suzuki coupling process entirely under acidic conditions, a series of reactions were conducted in buffered acidic media using several model substrates. 4-Chlorobenzylamine, in the presence of cataCXium®PtB, produced high yields of product at buffered pH 6.0; the yields dropped off precipitously at buffered pH 5.0 and lower. The fall-off in yield was attributed to the decomposition of the Pd–ligand complex due to the protonation of the ligand in the more acidic aqueous media. In contrast, in the absence of an added ligand, 4-amino-2-chloropyridine produced quantitative yields at buffered pH 3.5 and 4.5 while 4-amino-2-bromopyridine produced quantitative yields in a series of buffered media ranging from pH 4.5 to 1.5. These substrates are only partially protonated in acidic media and can behave as active Pd ligands in the Suzuki catalytic cycle.
Archive | 2010
Michael R. Loso; Benjamin M. Nugent; Yuanming Zhu; Richard B. Rogers; Jim X. Huang; James M. Renga; Gregory T. Whiteker; Nneka Breaux; John F. Daeuble
Archive | 2007
Michael R. Loso; Benjamin M. Nugent; Yuanming Zhu; Richard B. Rogers; Jim X. Huang; James M. Renga; Zoltan Benko; Gregory T. Whiteker; John F. Daeuble
Archive | 2012
Gregory T. Whiteker; Kim E. Arndt; James M. Renga; Yuanming Zhu; Christian T. Lowe; Thomas L. Siddall; David E. Podhorez; Gary A. Roth; Scott P West
Topics in Catalysis | 2010
Gregory T. Whiteker
Archive | 2014
Qiang Yang; Beth Lorsbach; Gary A. Roth; Noormohamed M. Niyaz; Jeffrey Nissen; Ronald Ross; Gregory T. Whiteker; Carl Deamicis; Kaitlyn Gray; Yu Zhang
Archive | 2010
James M. Renga; Gregory T. Whiteker; Kim E. Arndt; Christian T. Lowe