Abstract:
:Lewis base catalyzed bromo- and iodolactonization reactions have been developed and the effects of catalyst structure on rate and cyclization selectivity have been systematically explored. The effects of substrate structure on halolactonization reactions and the interaction of those effects with the effects of catalyst structure have been investigated, leading to synthetically useful improvements in cyclization selectivity. The knowledge acquired was applied to the development of Lewis base catalyzed bromo- and iodocycloetherification reactions. The ability of some of the surveyed catalysts to influence the cyclization selectivity of halolactonization reactions demonstrates their presence in the transition structure of the product-determining cyclization step. This observation implies that chiral derivatives of these catalysts have the potential to provide enantioenriched products regardless of the rates or mechanisms of halonium ion racemization.
journal_name
Proc Natl Acad Sci U S Aauthors
Denmark SE,Burk MTdoi
10.1073/pnas.1005296107subject
Has Abstractpub_date
2010-11-30 00:00:00pages
20655-60issue
48eissn
0027-8424issn
1091-6490pii
1005296107journal_volume
107pub_type
杂志文章abstract::To investigate the molecular basis for the tissue-specific expression of the human CD2 gene, its chromatin configuration was assessed by determining DNase I hypersensitivity and the degree of methylation during T-cell lineage commitment and development. Tissue-specific DNase I-hypersensitive sites were found within th...
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