REACTIONS OF 1,1-DIGALOCYCLOPROPANES WITH ELECTROPHILIC REAGENTS. SYNTHETIC ROUTE FOR INSERTING A CARBON ATOM BETWEEN THE ATOMS OF A DOUBLE BOND

1958 ◽  
Vol 80 (8) ◽  
pp. 2024-2025 ◽  
Author(s):  
Philip S. Skell ◽  
Stanley R. Sandler
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Synthetic Route ◽  
Electrophilic Reagents

scholarly journals Synthetic Route to Glycosyl β-1C-(phosphino)-phosphonates as Unprecedented Stable Glycosyl Diphosphate Analogs and Their Preliminary Biological Evaluation

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4969
Author(s):  
Michaël Bosco ◽  
Su-Jin Paik ◽  
Patricia Busca ◽  
Stuart E. H. Moore ◽  
Christine Gravier-Pelletier
Keyword(s):  
Alkaline Phosphatase ◽  
Double Bond ◽  
Biological Evaluation ◽  
Synthetic Method ◽  
Synthetic Route ◽  
Stereoselective Addition

The synthesis of glycosyl-β-1C-(phosphino)-phosphonates is a challenge since it has not yet been described. In this paper, we report an innovative synthetic method for their preparation from Glc-, Man-, and GlcNAc- lactone derivatives. The proposed original strategy involves the addition of the corresponding δ-hexonolactones onto the dianion of (methylphosphino) phosphonate as a key step, followed by dehydration and stereoselective addition of dihydrogen on the resulting double bond. Final deprotection provides the new glycosyl diphosphate analogs in 35%, 36%, and 10% yield over 6 steps from the corresponding δ-hexonolactones. The synthetized compounds were evaluated as inhibitors of phosphatase and diphosphatase activities and found to have complex concentration-dependent activatory and inhibitory properties on alkaline phosphatase. The synthetized tools should be useful to study other enzymes such as transferases.

Époxydes α-éthyléniques et phénate de sodium: accès à des éthers phénoliques et phénols ortho-allyliques

1985 ◽  
Vol 63 (9) ◽  
pp. 2449-2454 ◽  
Author(s):  
Michèle David ◽  
Jean Sauleau ◽  
Armelle Sauleau
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Steric Hindrance ◽  
Transition States ◽  
Ring Cleavage ◽  
Reaction Conditions ◽  
Carbon Compounds ◽  
Judicious Choice ◽  
Ethylenic Carbon ◽  
Cleavage Reactions

The ring cleavage reactions of α-ethylenic epoxides by sodium phenoxide afforded a mixture of products. Problems of competitive attack by this nucleophile, at the less substituted carbon (compounds A) or at the β-ethylenic carbon atom (compounds B and C), were encountered and could be resolved by judicious choice of reaction conditions (solvents, stereochemistry of the oxiranes). The regioselectivity of the attack was dependent on the transition states, implying weak steric hindrance and a conjugation oxirane – double bond.

Hétérobicycles oxygénés. Synthèse d'alkyl-3,6,8-trioxabicyclo[3.2.1]octanes et d'alkyl-3,7,9 et -4,7,9-trioxabicyclo[4.2.1]nonanes

1978 ◽  
Vol 56 (17) ◽  
pp. 2292-2300 ◽  
Author(s):  
Pierre Calinaud ◽  
Jacques Gelas
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Coupling Constants ◽  
Basic Medium ◽  
Main Interest ◽  
Proton Coupling ◽  
Geminal Proton

The cyclization in a basic medium of 2 (or 4)-chloroalkyl-4 (or 2) -hydroxyalkyl-1,3-dioxolanes leads to bicyclic acetals, the 3,6,8-trioxabicyclo[3.2.1]octanes, which are useful intermediates for synthesis, yielding notably functionalized 1,4-dioxanes. The nmr spectra of these heterobicyclics were studied. The geminal proton coupling constants permit oneto distinguish between five- and six-membered rings and the determination of couplings over several bonds (4J and 5J) yields information concerning the conformation of the model bicyclics.Two isomeric series of alkylated bicyclic acetals (3,7,9- and 4,7,9-trioxabicyclo[4.2.1]nonanes) are accessible by the following routes: (a) the intramolecular addition of a 4-hydroxy-alkyl group to the ethylenic double bond on the carbon atom a to C-2 in the 1,3-dioxolanes; (b) the dechlorohydration of 2-chloromethyl-4-hydroxyalkyl-1,3-dioxolanes; (c) the dehydration of dioxolane-diols. The main interest in these heterobicyclics is to prepare a seven-membered ring and to be able to prepare functionalized 1,4-dioxepanes. [Journal translation]

RELATIVE RATES OF REACTION OF OZONE WITH OLEFINS IN THE VAPOR PHASE

1960 ◽  
Vol 38 (7) ◽  
pp. 1053-1062 ◽  
Author(s):  
T. Vrbaski ◽  
R. J. Cvetanović
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Vapor Phase ◽  
Reaction Products ◽  
Initial Formation ◽  
Inhibiting Effect ◽  
Π Complex ◽  
Olefinic Double Bond

Relative rates of reaction of ozone with a number of olefins in the vapor phase have been determined by the use of the competitive method and GLC analysis of the reaction products. The results indicate a basic electrophilic trend onto which is superimposed a trend due to a partially inhibiting effect of the substituent groups, in particular of those on the more substituted carbon atom of the olefinic double bond. The results are discussed particularly in terms of a two-step addition process, involving an initial formation of an ozone–olefin π-complex and a slower rearrangement of the π-complex into the cyclic "initial ozonide".

Chemical Constituents of Corchorus capsuJaris and C. olitorius (Jute Plant), III. Structure of Corosin

1974 ◽  
Vol 29 (5-6) ◽  
pp. 209-221 ◽  
Author(s):  
M. Manzoor-i-Khuda ◽  
Gerhard Habermehl
Keyword(s):  
Acetic Acid ◽  
Double Bond ◽  
Carbon Atom ◽  
Sulphuric Acid ◽  
Main Product ◽  
Chemical Constituents ◽  
Dioic Acid ◽  
Acetate Ester ◽  
Acid Reagent

Corosin (8; R = R1 = H) has been reisolated through a modified procedure, as its acetate (8; R=H, R1 = Ac), in an overall yield of 0.2% from jute roots. On pyrolysis in vacuo, corosin gave pyro corosin (1a; R1 = OH, R2= COOH, R3 = R5 = H, R4 = R6 = Me), shown to have a 12:18 (17) di-ene formed by elimination of the 19-OH and the angular C-28 carboxyl in the molecule. On rearrangement with concentrated sulphuric acid in acetic acid, corosin acetate gave corosin anhydro lactone acetate (7; R1 = Ac, R = H), having a 13(18) double bond and a lactone bridge between the 28-carboxyl and the 20-carbon atom. Corosin acetate ester (8; R = Me, R 1 = Ac), on treatment with sulphuric-acetic acid reagent, gave as the main product anhydro corosin acetate ester (7; R = Me, R1= A c), with a 12:18(19)-diene. The structure of corosin is proposed to be urs-12-ene-2α, 3β, 19α-trihydroxy-24, 28-dioic acid (8; R = R1= H).

Recent investigations on the nature of sterol intermediates in the biosynthesis of cholesterol

1972 ◽  
Vol 180 (1059) ◽  
pp. 125-146 ◽  
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Rat Liver ◽  
Liver Homogenate ◽  
Methyl Groups ◽  
Double Bonds ◽  
Animal Tissues ◽  
Methyl Group ◽  
Chromatographic Methods

Lanosterol(4,4,14α-trimethyl-cholesta-8,24-dien-3β-ol) has been proposed as the primary product of the cyclization of 2,3-epoxysqualene in animal tissues. Enzymic conversion of lanosterol to cholesterol requires reduction of the ∆ 24 double bond, removal of the three extra methyl groups, and shift of the nuclear double bond from ∆ 8 position to the ∆ 5 position. Until very recently, all of the proposed sterol intermediates in the biosynthesis of cholesterol possessed nuclear double bonds in the ∆ 8 , ∆ 7 , ∆ 5,7 or ∆ 5 positions. Consideration of possible mechanisms for the removal of the methyl group at carbon atom 14 of sterol precursors led to our demonstration of the presence of cholest-8(14)-en-3β-ol in animal tissues and establishment of the convertibility of this sterol to cholesterol in rat liver homogenate preparations. Reports (from other laboratories) of the stereospecific loss of the 15α-hydrogen of lanosterol upon enzymic conversion to cholesterol led to the demonstration of the convertibility of cholesta-8,14-dien-3β-ol, cholesta-7,14-dien-3β-ol, 14α-methyl-cholest-7-en-3β,15-diol, cholest-8(14)-en-3β,15α-diol, and cholest-8(14)-en-3β,15β-diol to cholesterol in rat liver preparations. We have recently developed chromatographic methods permitting the resolution of all of the C 27 sterols in question. The results of recent experiments directed towards an understanding of the detailed metabolism of these compounds are presented herein.

A NEW SYNTHESIS OF METHYL β-D-GULOPYRANOSIDE

1960 ◽  
Vol 38 (10) ◽  
pp. 1917-1920 ◽  
Author(s):  
N. J. Antia ◽  
M. B. Perry
Keyword(s):  
Carbon Atom ◽  
Sodium Borohydride ◽  
Convenient Method ◽  
Reaction Scheme ◽  
Synthetic Route ◽  
Sodium Metaperiodate ◽  
New Synthesis

The oxidation of 1 mole of β-D-glycero-D-gulo-heptopyranoside with 1 mole of sodium metaperiodate, followed by reduction with sodium borohydride, gave rise to crystalline methyl β-D-gulopyranoside. The method provides a new synthetic route to the D-guloside and, thence, to D-gulose. The possibility of utilizing this reaction scheme as a general convenient method for preparing the relatively rare aldohexoses as well as for "labelling" carbon atom 1 of these compounds is discussed.

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