Some Observations on Allylic Oxidation<sup>1</sup>

Wiberg, Kenneth B.; Nielsen, Stuart D.

doi:10.1021/jo01034a055

Cited by 110 publications

(46 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, stoichiometric amounts of SeO 2 under slightly basic conditions (pyridine in toluene) was the alternative. It is well-known that asymmetrically substituted olefins direct the oxidation reaction to the more-substituted end of the olefin, and that the reactivity decreases in the order CH 2 b CH 3 b CH [11]. Indeed, compound 1 was cleanly oxidized (60 ± 75% yield) with high regioselectivity at C(30), giving rise to the a,b-unsaturated aldehyde 24.…”

mentioning

confidence: 99%

Improved Anti-Inflammatory Activity of Three New Terpenoids Derived, by Systematic Chemical Modifications, from the Abundant Triterpenes of the Flowery PlantCalendula officinalis

Neukirch

D’Ambrosio

Sosa

et al. 2005

C&B

View full text Add to dashboard Cite

Rings A, D and E of faradiol (1), and ring E of both arnidiol (10) and calenduladiol (4) have been subjected to various selective chemical manipulations to modify polarity, water affinity, H-bonding, sterics, and number of aromatic groups of these anti-inflammatory natural compounds. A total of 15 new and four known pentacyclic triterpenoids have been obtained in this way. Some 13 terpenoids were evaluated for their topical anti-inflammatory activities with respect to inhibition of croton oil induced ear oedema in mouse. Three derivatives of 1, the C(16) benzyl ether 15, the C(30) aldehyde 24, and the C(30) primary alcohol 25 showed significantly improved anti-inflammatory potencies, which is relevant for (future) structure-activity-relationship (SAR) studies.

show abstract

mentioning

confidence: 99%

Improved Anti-Inflammatory Activity of Three New Terpenoids Derived, by Systematic Chemical Modifications, from the Abundant Triterpenes of the Flowery PlantCalendula officinalis

Neukirch

D’Ambrosio

Sosa

et al. 2005

C&B

View full text Add to dashboard Cite

show abstract

“…10 Among other functions occurring after phage infection that have been suspected of involving DNase activity are: (a) genetic exclusion of related, superinfecting phage23 (this function is retained by gene 46 or 47 mutants'7); (b) breakdown of the DNA of superinfecting phage24 (this is under study); (c) genetic recombination25 26 (this process is virtually unimpaired when gene 46 or 47 does not function). 17 Summnary.-Mutants in a number of genes of bacteriophage T4 were examined for their ability to cause breakdown of bacterial DNA after infection. To do this, a second mutation, one that completely blocks phage DNA synthesis, was "bred" into those mutants not already fully blocked in DNA synthesis, thus allowing direct observation of the fate of the bacterial DNA.…”

mentioning

confidence: 99%

Mutants of bacteriophage T4 unable to cause breakdown of host DNA.

Wiberg¹

1966

Proc. Natl. Acad. Sci. U.S.A.

100

View full text Add to dashboard Cite

T-even bacteriophage have been reported to induce the appearance of three new DNases", 2 after infection of E. coli, which itself contains at least six DNases.3 4 The specific intracellular function of these enzymes is unknown, although E. coli exonuclease IP and a T2 and a T4 exonuclease are found closely associated with DNA polymerase.2b 6 Radding7 has shown that mutations in the N cistron of bacteriophage X that block phage replication also result in a failure of the X-associated nuclease to appear. Radding8 has also shown that a lethal mutation in a different cistron of phage X causes the synthesis of abnormally high levels of this enzyme. Mutations affecting the DNases of T-even phage have not been described, however. This report describes one approach designed to discover such mutants.Hershey et al. demonstrated that shortly after infection of E. coli by T2 the bacterial DNA is degraded.9 When one measures total DNA as a function of time after infection by wild-type T-even phage, this DNA breakdown is obscured completely by concomitant synthesis of phage DNA. However, if infection is carried out with a mutant of T4 that is unable to induce synthesis of any phage DNA, one observes clearly and directly the conversion of a large proportion of the bacterial DNA from an acid-insoluble to an acid-soluble form.10 Since this conversion almost certainly involves a DNase, it is probable that a mutant unable to cause this conversion will be defective in a gene controlling a phage-specific DNase. Therefore, in the present study, mutants in most of the known genes of phage T4 affecting phage DNA synthesis, among others, were tested for their ability to cause breakdown of the host DNA. Since many such mutants induce the synthesis of at least some phage DNA, it was necessary to block their phage DNA synthesis in order to observe directly the fate of the bacterial DNA; this was done by introducing a second mutation, am N55 in gene 42,"' 12 into each mutant tested. With this technique, it was found that mutants in genes 46 and 47 are unable to cause breakdown of the bacterial DNA. Some properties of these mutants are presented, including other circumstantial evidence that they control one or more DNases.Materials and Methods.-Bacteria and phage were always grown in glycerol casamino acid medium,'3 herein termed GCA. Phage were assayed at 300 with the agar-layer techniquel4a with 0.2 ml of a fresh 3-hr culture of E. coli CR63 (at about 5 X 108 cells/ml) in 3 ml of top layer. The top layer was 0.6% Bacto agar in GCA; the bottom layer was 1% Bacto agar in GCA. Bacto nutrient broth in 0.5% NaCl (NB-NaCl) was used as diluent when assaying phage. For maximal recovery of colony formers when assaying viable bacteria, it was necessary to dilute through, and plate on, GCA.Phage and bacterial stocks: Stocks of E. coli B (nonpermissive for T4 am mutants) and E. coli CR63 (permissive for T4 am mutants), as well as T4 mutants am N130 and am N116 (called an 130 and am 116, respectively, in ref. 10) were obtained from R. Epstein via J. M. ...

show abstract

“…Formation of the (Huguet, 1967;Olson, 1966;Schaefer et al, 1968;Wiberg and Nielsen, 1964). The failure to detect any diol among the products is well explained by this scheme, which indicates that monoacetates were primary reaction products and did not result from esterification of the alcohols.…”

Section: Identification Of Prodnctsmentioning

confidence: 94%

“…Ample precedents for the mechanism of selenium dioxide oxidation of olefins are found in the literature, and in recent years attention has also been focused on the role of the organoselenium compounds in elucidating the reaction schemes (Huguet, 1967;Olson, 1966;Schaefer et al, 1968;Wiberg and Nielsen, 1964). Ample precedents for the mechanism of selenium dioxide oxidation of olefins are found in the literature, and in recent years attention has also been focused on the role of the organoselenium compounds in elucidating the reaction schemes (Huguet, 1967;Olson, 1966;Schaefer et al, 1968;Wiberg and Nielsen, 1964).…”

Section: Identification Of Prodnctsmentioning

confidence: 99%