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Oxiranic ring activation

The first step of PO addition to hydroxyl groups is the SN-2 attack of the tertiary nitrogen atom to the a-carbon atom of the oxiranic ring, activated by a hydrogen bond between the oxiranic oxygen and hydrogen atom of hydroxyl groups (reaction 13.6). [Pg.328]

The principle of active-site-directed inactivation of glycosidases by gly-con-related epoxides can be extended to compounds having an exocyclic oxirane ring, either directly attached to the six-membered ring (32) or at some distance (33,34). Studies with -o-glucosidase from sweet almonds and intestinal sucrase-isomaltase revealed that, in spite of the higher intrinsic reactivity of these epoxides, this shift of the position of the epoxide function causes a 10- to 30-fold decrease of kj(max)/Ki, an effect which probably reflects the limited flexibility of the catalytic groups involved in the epoxide reaction. [Pg.370]

Organotin epoxide monomers 30,100 104) containing fairly reactive oxirane rings and both C=C and Sn—C bonds can be used as starting components for the synthesis of new polymers, chemically active stabilizers and biocides for polymeric materials, e.g. for PVC. [Pg.129]

In 1993, Yoshida et al. pubhshed trapoxin (TPX, Fig. 3), a fimgal product, which, in contrast to TSA, is an irreversible inhibitor of mammalian histone deacetylase [38]. When the epoxide moiety is reduced to the corresponding primary alcohol, HDAC inhibiting activity is completely lost. This observation emphasizes the importance of the oxirane ring, which most likely binds irreversibly via ring opening at the activated 2-position to a nucleophihc active site residue. [Pg.301]

Biologically active cyclic tetrapeptides (4-7) showed (1) a conformational preference in the epoxyketone moiety (2) no n -+ jt peptide bond contribution to As near 288 nm and (3) anti-octant perturbation of oxirane ring. [Pg.177]

Oxetanes are generally much more stable to nucleophilic attack than the more strained three-membered ring oxiranes. However, activation of the oxygen atom by a Lewis acid increases the electronegativity of the adjacent carbon atom and renders oxetanes susceptible to attack from a nucleophile accompanied by subsequent ring opening. [Pg.331]


See other pages where Oxiranic ring activation is mentioned: [Pg.363]    [Pg.492]    [Pg.363]    [Pg.492]    [Pg.192]    [Pg.546]    [Pg.183]    [Pg.199]    [Pg.48]    [Pg.569]    [Pg.634]    [Pg.636]    [Pg.755]    [Pg.306]    [Pg.158]    [Pg.56]    [Pg.256]    [Pg.162]    [Pg.473]    [Pg.269]    [Pg.615]    [Pg.150]    [Pg.2]    [Pg.20]    [Pg.202]    [Pg.1195]    [Pg.1197]    [Pg.202]    [Pg.218]    [Pg.1097]    [Pg.304]    [Pg.21]    [Pg.181]    [Pg.72]    [Pg.114]    [Pg.192]    [Pg.21]    [Pg.41]    [Pg.192]    [Pg.136]    [Pg.136]    [Pg.70]    [Pg.108]    [Pg.3]   
See also in sourсe #XX -- [ Pg.335 ]




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Oxirane ring

Ring activation

Ring oxiranes

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