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61.
David B. Capps Orson D. Bird Edward F. Elslager Zoe B. Gavrilis Jane A. Roush Paul E. Thompson John W. Vaitkus 《Journal of heterocyclic chemistry》1968,5(3):355-369
The preparation of a variety of novel 1-aryl-4,6-diamino-1,2-dihydro-s-triazines is described. These compounds exhibit an array of contrasting effects on intestinal helminths, bacteria, and dihydrofolic reductase. It is concluded that potent anthelmintic activity among the dihydro-triazines is not dependent solely on the bulky-substituent hypothesis advanced by other investigators, and indeed cannot reliably be predicted on this basis. 相似文献
62.
Lindlar hydrogenation of substituted methyl (,)-deca-7,9-dien-2-ynoates and substituted methyl (,)-undeca-8,10-dien-2-ynoates affords selectively the corresponding (,,)-trienes. 相似文献
63.
[Structure: See text] Double asymmetric [3 + 2]-annulation reactions of chiral beta-silyloxyallylsilanes with chiral 2-tetrahydrofuranyl carboxaldehydes have been studied, leading to the stereocontrolled synthesis of six diastereomeric bis-tetrahydrofuran structures corresponding to the core subunits of members of the Annonaceous acetogenin family of natural products. Transition-state models are proposed to account for the stereoselectivity of the double-stereodifferentiating [3 + 2]-annulation reactions. 相似文献
64.
We show that a finite lattice is isomorphic to the lattice of ideals in a regular ring if and only if it is distributive. We also study the countable case. 相似文献
65.
[reaction: see text] Syntheses of conduritols B-D and F and d-(+)-chiro- and neo-inositols from cyclohexenylsilane intermediates are described. The key cyclohexylsilane intermediates 5 and 14 were synthesized by stereoselective olefin dihydroxylation of the corresponding cyclohexenylsilanes. Selective Peterson elimination reactions and Fleming-Tamao oxidations of 5 and 14 then delivered the targeted cyclitol derivatives. 相似文献
66.
[reaction: see text] A concise synthesis of the spinosyn A tricyclic nucleus 27 has been developed by a route featuring a one-pot tandem intramolecular Diels-Alder reaction and intramolecular vinylogous Morita-Baylis-Hillman cyclization in which five stereocenters in tricycle 10 are set with excellent selectivity. 相似文献
67.
We consider the impact of fluctuations in the technology matrix A on two command input- output models. In the first, resources and goals are fixed and the model is solved for industrial production. If the growth rate can be zero, expected values of fluctuations of industrial goods are infinite. In the second, produced goods are scaled down to fit resources. Here we derive a criterion that should be small, where k is the number of significant ingredients in a good efficiency of aggregated economies, with n replaced by n1/2 where n1 is the number of goods aggregated into one. 相似文献
68.
[formula: see text] A highly diastereoselective synthesis of 3, corresponding to the C(5)-C(21) segment of tedanolide, has been accomplished by a route utilizing the aldol reaction of aldehyde 4 and the beta,gamma-unsaturated methyl ketone 5. 相似文献
69.
[reaction: see text] The racemic cis-decalin core fragment 30 of integramycin was synthesized by a sequence involving a highly diastereoselective intramolecular Diels-Alder reaction of triene 24. A remarkable switch in stereoselectivity occurred upon changing the dienophile unit of 24 from (Z)- to (E)-geometry. 相似文献
70.
A highly diastereoselective synthesis of the top half (4) of kijanolide is described. The key step is the exo and diastereoface selective Diels-Alder reaction of triene 6 and chiral dienophile 6. 相似文献