Search results for "Single class"
showing 5 items of 5 documents
Eight-membered Rings with Two Heteroatoms 1,3
2008
This chapter deals with heterocine rings with two heteroatoms in a 1,3-relationship, namely 1,3-diazocine, 2H-1,3-oxazocine, 2H-1,3-thiazocine, 4H-1,3-dioxocin, and 4H-1,3-dithiocin. On the 4H-1,3-oxathiocin ring system, belonging to the diheterocine family, in the past decade, no chemistry was reported. This chapter covers the literature from 1996 to 2006 and also reports those articles published in 1995 which were not reported in CHEC-II(1996). In this edition, in addition to the uncondensed derivatives, eight-membered 1,2-heterocycles fused to five-, six-, and seven-membered carbocycles or heterocycles are covered. Bridged heterocines, which actually constitute the majority of the compou…
Eight-membered Rings with Two Heteroatoms 1,5
2008
The chapter of the third edition of Comprehensive Heterocyclic Chemistry (CHEC III) 12.24 titled ‘Eight-membered Rings with two Heteroatoms 1,5’ deals with diheterocines rings with two heteroatoms in a 1,5 relationship, namely 1,5-diazocine, 1,5-oxazocine, 1,5-thiazocine, 1,5-dioxocin, 1,5-oxathiocin, and 1,5-dithiocin. This chapter covers the literature from 1996 to 2006 and also reports those articles published in 1995 which were not reported in CHEC-II(1996). In this edition, in addition to the uncondensed derivatives, eight-membered 1,5-heterocycles fused to five-, six-, and seven-membered carbocycles or heterocycles are covered. Bridged diheterocines, which actually constitute the majo…
Superinvolutions on upper-triangular matrix algebras
2018
Let UTn(F) be the algebra of n×n upper-triangular matrices over an algebraically closed field F of characteristic zero. In [18], the authors described all abelian G-gradings on UTn(F) by showing that any G-grading on this algebra is an elementary grading. In this paper, we shall consider the algebra UTn(F) endowed with an elementary Z2-grading. In this way, it has a structure of superalgebra and our goal is to completely describe the superinvolutions which can be defined on it. To this end, we shall prove that the superinvolutions and the graded involutions (i.e., involutions preserving the grading) on UTn(F) are strictly related through the so-called superautomorphisms of this algebra. We …
Eight-membered Rings with Two Heteroatoms 1,2
2008
This chapter deals with heterocine rings with two heteroatoms in a 1,2-relationship, namely 1,2-diazocine, 2H-1,2-oxazocine, 2H-1,2-thiazocine, 1,2-dioxocin, 1,2-oxathiocin, and 1,2-dithiocin. This chapter covers the literature from 1996 to 2006 and also reports those articles published in 1995 which were not reported in CHEC-II(1996). In this edition, in addition to the uncondensed derivatives, eight-membered 1,2-heterocycles fused to five-, six-, and seven-membered carbocycles or heterocycles are covered, although in one case a four-membered fused cycle was occasionally reported. Bridged heterocines, which actually constitute the majority of the compounds reported, are covered as well. Th…
Expressing digression linguistically: Do digressive markers exist?
2009
Abstract This paper analyzes the relationship between digressions and topic shifts in the light of the Spanish marker por cierto . Against the standard explanation, which takes digression as a well-established linguistic operation, digression is regarded as a rhetorical operation, underspecified at the linguistic level. The most conspicuous trace of digression, the so-called digressive markers , cannot be distinguished from topic shifters on the basis of the instruction provided by the marker alone. Thus, both types of markers should be grouped together as a single class, that of “new relevant information markers” (NRIMs). The perceived differences between topic shifters and digressive mark…