‘Forbidden’ Electrocyclizations of Diradicaloids
نویسندگان
چکیده
منابع مشابه
Biosynthetic and biomimetic electrocyclizations.
Pericyclic reactions have long been considered a biosynthetic rarity. In contrast to their prominence in the laboratory, they seemed to play only minor roles in Nature. Over the past decades, however, enough examples have been amassed to demonstrate that pericyclic reactions occur quite frequently in biosynthetic pathways. Pericyclic reactions include cycloadditions, sigmatropic rearrangements,...
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In this work, we introduce and study the forbidden-vertices problem. Given a polytope P and a subset X of its vertices, we study the complexity of linear optimization over the subset of vertices of P that are not contained in X . This problem is closely related to finding the k-best basic solutions to a linear problem. We show that the complexity of the problem changes significantly depending o...
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A simple matrix is a (0, 1)-matrix with no repeated columns. For a (0, 1)matrix F , we say that a (0, 1)-matrix A has F as a configuration if there is a submatrix of A which is a row and column permutation of F (trace is the set system version of a configuration). Let ‖A‖ denote the number of columns of A. Let F be a family of matrices. We define the extremal function forb(m,F) = max{‖A‖ : A is...
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We consider the problem of indexing a collection of documents (a.k.a. strings) of total length n such that the following kind of queries are supported: given two patterns P and P−, list all nmatch documents containing P but not P−. This is a natural extension of the classic problem of document listing as considered by Muthukrishnan [SODA’02], where only the positive pattern P is given. Our main...
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ژورنال
عنوان ژورنال: Trends in Chemistry
سال: 2019
ISSN: 2589-5974
DOI: 10.1016/j.trechm.2019.08.005