摘要:

The esr spectrum of (CH3)313COO•has been observed in solution and the hyperfine interaction with the carbon-13 nucleus is 3.92 G.

ISSN:0008-4042    

DOI:10.1139/v79-042

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The values of the Brønsted exponent for several examples of nucleophilic substitution reactions, aromatic electrophilic substitution reactions, and hydrogen atom abstraction from toluene by free radicals have been calculated from the ρ values of the corresponding reactions. The magnitude of the Brønsted exponent is shown to indicate the degree of charge developed in the transition state structure.

ISSN:0008-4042    

DOI:10.1139/v79-043

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A number of α,β-epoxy sulfoxides and epoxy sulfones have been prepared via cyclization of α-chloro-β-hydroxy sulfoxides or phase-transfer catalyzed reaction between α-chloroalkyl sulfones and carbonyl compounds. Thermal and acid-catalyzed rearrangement of these epoxides resulted in migration of sulfinyl or sulfonyl groups to form β-carbonyl sulfoxides or sulfones. Upon treatment of the epoxy sulfones with MgBr2in ether, α-bromocarbonyl compounds were obtained in excellent yield. The reaction of epoxy sulfones with nucleophiles was also briefly investigated.

ISSN:0008-4042    

DOI:10.1139/v79-044

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Two peptides, H-Gly Ser Phe Lys-NH2and H-Gly Ser Phe Lys Leu-NH2, whose sequence may be found in a conserved and phosphorylated site in histone H-1 have been synthesized. Their ability to act as substrates for several protein kinase preparations have been examined. In addition, their ability to inhibit the action of several protein kinases of muscle origin was also tested.

ISSN:0008-4042    

DOI:10.1139/v79-045

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A multistage sequence gave 5′-O-pivalyl-3′-O-methyladenosine (2e) which was treated with thionyl chloride in hot pyridine to give the corresponding 2'-chloro-arabinoproduct3a. Hydrogenolysis using tri-n-butyltin hydride and deblocking gave 2′-deoxy-3′-O-methyl-adenosine (3b). Analogous treatment of a mixture of 3′(2′),5′-di-O-acetyladenosines (5a,b) with SOCl2-pyridine gave the 3′-O-acetyl-2′-chloro-arabino(6a) and 2′-O-acetyl-3′-chloro-xylo(7a) derivatives in a ratio of ∼3:2, respectively. Hydrogenolysis and deprotection gave 2′-deoxyadenosine (6c) and 3′-deoxyadenosine (7c) (∼3:2) in ∼45% overall yield from adenosine (based on recovered starting materials). This represents the first example of preferential external nucleophilic displacement at C-2′ (vs. C-3′) in an equilibrating purine ribonucleoside system. Treatment of 9-β-D-xylofuranosyladenine (9) with SOCl2–HMPA gave the 5′-chloro-5′-deoxy product10arather than the previously suggested 2′-chloro-2′-deoxy derivative.

ISSN:0008-4042    

DOI:10.1139/v79-046

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The singlet1Φ and triplet3Φ excited state product yields produced on thermolysis in toluene of trimethyl- (1), tetramethyl- (2),cis-3, 4-butano-3,4-dimethyl- (3), and 3,4:3,4-dibutano-1,2-dioxetane (4) were determined to be as follows (dioxetane, °C,1Φ,3Φ):1, 40, 1.1 × 10−3, 0.15;2, 45, 4.4 × 10−4, 0.31;3, 26, 8.5 × 10−4, 0.23;4, 24, 4.8 × 10−6, 0.011. The reason for the low yield of excited states obtained from4is not known. Thermochemical calculation indicate that as much energy is available from thermolysis of4as is available from2.Dioxetane-energized dimerization of acenaphthylene, accompanied by an intense yellow luminescence, produced mainly thetransdimer in 1–3% yield. Dioxetane-energized cyclization of 1-(2,4-dimethylphenyl)-1,2-propanedione produced 2-hydroxy-2,5-dimethylindan-1-one in 0.5–6% yields.

ISSN:0008-4042    

DOI:10.1139/v79-047

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A synthesis of 16,17-dihydrosecodin-17-ol and of secodine is described. Various indole derivatives were elaborated to a series of pyridinium salts, potential precursors for 1,2- and 1,6-dihydropyridine compounds exemplifying the proposed biointermediate 'dehydrosecodine.'

ISSN:0008-4042    

DOI:10.1139/v79-048

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Controlled reduction ofN-methyl-3-ethylpyridinium iodide afforded the corresponding 1,2-dihydropyridine which was stabilised by complexation to give 1,2- and 1,6-dihydro-3-ethyl-N-methylpyridinetricarbonylchromium(0). These stable, isomeric complexes were interrelated by thermal equilibration. Analogous sequences with more complex, alkaloid derivatives enabled formation, and stabilisation by complexation, of 1,2- and 1,6-dihydropyridines in the presence of other functions such as the indole unit and ester groups.

ISSN:0008-4042    

DOI:10.1139/v79-049

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The dilithium derivatives of the ditertiary 1,2-diols,cis- andtrans-1,2-dimethyl-1,2-cyclo-hexanediol, fail to undergo base-induced stereochemical equilibration under conditions that lead to such equilibration with the dilithium derivatives of the disecondary 1,2-diols,cis- andtrans-1,2-cyclohexanediol. This casts doubt on the proposal that the latter equilibration proceeds by carbon–carbon bond cleavage of the dialkoxide to give a diketyl intermediate. It is highly probable that it involves oxidation–reduction as established by Doering in the case of monohydric alcohols. Examination of steroidal secondary-tertiary 1,2-diols under similar conditions shows that such systems can epimerize at both carbinol centres; this is interpreted in terms of sequential oxidation, α-ketol rearrangement, and reduction.

ISSN:0008-4042    

DOI:10.1139/v79-050

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

N-3′-Furylbenzamide gives a conventional Diels–Alder adduct with maleic anhydride but with dimethyl maleate and methyl acrylate further reactions take place at the enamide grouping of the initially formed adducts. Compounds have been isolated in which molecules of an alcohol, used as solvent, or the starting furan have added to the double bond of the 1:1 adducts. In the first case unstable alkoxyamides are formed; in the second stable 2:1 adducts result from a novel uncatalysed addition to the double bond of the enamide. The stereochemistry of these and related compounds is discussed.

ISSN:0008-4042    

DOI:10.1139/v79-051

出版商:NRC Research Press    

年代:1979

数据来源: NRC