Novel Rearrangements of the 2-Chloroacrylonitrile Cycloadducts of Steroidal 14,16-Dien-17-yl Acetates

2001 ◽  
Vol 66 (12) ◽  
pp. 1777-1796 ◽  
Author(s):  
James R. Bull ◽  
Richard S. Gordon ◽  
Claudia Grundler
Keyword(s):  
Functional Group ◽  
Major Product ◽  
Similar Reaction ◽  
Rearrangement Product ◽  
Methyl Derivative ◽  
Bond Scission ◽  
Grob Fragmentation

Cycloaddition of 3-methoxyestra-1,3,5(10),14,16-pentaen-17-yl acetate (1) with 2-chloroacrylonitrile furnishes 17β-acetoxy-16α-chloro-3-methoxy-14,17α-ethenoestra-1,3,5(10)-triene-16β-carbonitrile (2) as the major product, which undergoes alkali-mediated rearrangement to (161R)-3-methoxy-17-oxo-16β,15β,14-(ethane[1,1,2]triyl)-14β-estra-1,3,5(10)-triene-161-carbonitrile (7). A similar reaction course is followed by the related 16-methyl derivative 4, and it is shown that minor 15-chloro-15-cyano cycloadducts 3 and 6 undergo Grob fragmentation. Functional group manipulations and regioselective bond-scission processes are described, for conversion of rearrangement product 7 into 16β,15β,14-(ethane[1,1,2]triyl) and cyclobuta[14β,15β] analogues of estradiol.

scholarly journals Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones

2020 ◽  
Vol 11 (39) ◽  
pp. 10759-10763
Author(s):  
Jinzhong Yao ◽  
Zhangpei Chen ◽  
Lin Yu ◽  
Leiyang Lv ◽  
Dawei Cao ◽  
...  
Keyword(s):  
Functional Group ◽  
Bond Scission ◽  
Terminal Alkenes ◽  
Palladium Catalyzed ◽  
High Yields

A palladium-catalyzed hydroalkylation of methylenecyclopropanes via selective C–C σ-bond scission was achieved, in which simple hydrazones served as carbanion equivalents. This method affords high yields of C-alkylated terminal alkenes with good functional group compatibility.

Synthesis of new substituted dihydroheptalene derivatives: SiO2- and base-catalyzed rearrangement of dimethyl trans-3,8-dihydroheptalene-3,8-dicarboxylate

2001 ◽  
Vol 79 (1) ◽  
pp. 35-41
Author(s):  
Nurullah Saraçoglu ◽  
Abdullah Menzek ◽  
Armagan Kinal ◽  
Metin Balci
Keyword(s):  
Room Temperature ◽  
Heat Of Formation ◽  
Major Product ◽  
Similar Reaction ◽  
Am1 Calculations ◽  
Hydrogen Shift ◽  
Proton Shift ◽  
Major Isomer ◽  
Prolonged Reaction Time ◽  
Lower Heat

Dimethyl trans-3,8-dihydroheptalene-3,8-dicarboxylate (trans-3) isomerizes to dimethyl cis-3,8-dihydroheptalene-3,8-dicarboxylate (cis-3) upon treatment with SiO2. On the other hand, base-catalyzed reaction of trans-3 undergoes a direct 1,3-intramolecular proton shift to give 6 at room temperature in 5 min. Prolonged reaction time formed isomers 7 and 8 in a ratio of 4:1. AM1 calculations indicate that the isomer 8, which is formed as minor product, has a lower heat of formation (–99.34 kcal mol–1) than that of the major isomer 7 (–92.05 kcal mol–1). However, when a similar reaction was performed at 100°C, the thermodynamically more stable isomer 8 was formed as the major product. Furthermore, cycloaddition reactions of these new dihydroheptalene derivatives 6 and 7 with different dienophiles have been studied. The mechanism has been discussed.Key words: dihydroheptalene, cycloaddition, 1,3-hydrogen shift, cycloheptatriene–norcaradiene equilibrium.

Synthesis of some partially methylated sucrose derivatives

1972 ◽  
Vol 25 (2) ◽  
pp. 407 ◽  
Author(s):  
GW O'Donnell ◽  
GN Richards
Keyword(s):  
Boron Trifluoride ◽  
Liquid Ammonia ◽  
Major Product ◽  
Methyl Derivative ◽  
Hydrolysis Products ◽  
Subsequent Deacetylation ◽  
Partially Methylated

1',6,6'-Tri-O-methylsucrose, a new compound, has been synthesized by methylation of 2,3,3',4,4'-penta-O-acetylsucrose with diazomethane and boron trifluoride with subsequent deacetylation. 2,3,3',4,4'-Penta-O-methylsucrose has been obtained in improved yield from the tri-O-trityl derivative by reduction with lithium in liquid ammonia. A major product of the incomplete methylation of 11,6,6'-tri-O-tritylsucrose was the 2,3,3',4'-tetra-O-methyl derivative, and after reductive detritylation 2,3,3',4'-tetra-O-methylsucrose, a new compound, was isolated and identified by examination of its hydrolysis products.

Differentiation of the C–O and C–C bond scission mechanisms of 1-hexadecanol on Pt(111) and Ru(0001): a first principles analysis

2017 ◽  
Vol 7 (3) ◽  
pp. 743-760 ◽  
Author(s):  
Meng-Ru Li ◽  
Gui-Chang Wang
Keyword(s):  
First Principles ◽  
Major Product ◽  
Bond Scission

The major product on Pt(111) is hexadecane, whereas it is pentadecane on Ru(0001).

scholarly journals Cumene hydroperoxide-dependent oxidation of NNN'N'-tetramethyl-p-phenylenediamine and 7-ethoxycoumarin by cytochrome P-450. Comparison between the haemoproteins from liver and olfactory tissue

1989 ◽  
Vol 261 (3) ◽  
pp. 793-800 ◽  
Author(s):  
C J Reed ◽  
F De Matteis
Keyword(s):  
Olfactory Epithelium ◽  
Peroxidase Activity ◽  
Cumene Hydroperoxide ◽  
Major Product ◽  
Radical Scavenger ◽  
Heterolytic Cleavage ◽  
Nasal Tissue ◽  
Bond Scission ◽  
Olfactory Tissue ◽  
Cytochrome P 450

The interaction of cytochromes P-450 of the liver and olfactory epithelium of male hamsters with cumene hydroperoxide (CHP) has been characterized with regard to the ability of CHP to (1) support 7-ethoxycoumarin-O-de-ethylase (ECOD) activity, (2) support the oxidation of NNN'N'-tetramethyl-p-phenylenediamme (peroxidase activity) and (3) cause inactivation of cytochrome P-450. In the liver, CHP was found to support both ECOD and peroxidase activities while causing only minimal inactivation of cytochrome P-450. In contrast, in the olfactory epithelium CHP was virtually unable to support ECOD activity, peroxidase activity was 4-fold greater than in the liver, and extensive inactivation of cytochrome P-450 occurred. The reasons for these differences have been investigated with particular reference to the mode of cytochrome P-450-catalysed decomposition of CHP, that is, via homolytic or heterolytic cleavage of the hydroperoxide dioxygen bond. In both tissues, cumenol (2-phenylpropan-2-ol) was the major product of CHP decomposition detected. The radical scavenger nitrosobenzene inhibited cumenol formation by 84% in the olfactory epithelium, but by only 38% in the liver. This may indicate that dioxygen-bond scission occurs predominantly homolytically in the nasal tissue, whereas there is a balance between homolysis and heterolysis in the liver. It is suggested that the inability of CHP to support ECOD activity in the olfactory epithelium and the extensive inactivation of cytochrome P-450 that it causes both stem from decomposition of the hydroperoxide occurring homolytically rather than heterolytically in this tissue.

Stereoselectivity of C(3)-methylation of camphor and derivatives

1984 ◽  
Vol 62 (10) ◽  
pp. 1899-1902 ◽  
Author(s):  
John H. Hutchinson ◽  
Thomas Money
Keyword(s):  
Major Product ◽  
Methyl Derivative

Contrary to general expectations, kinetic methylation of camphor, 9-bromocamphor, or 9,10-dibromocamphor produces the 3-exo-methyl derivative as the major product.

Synthesis of Some Thieno Analogs of the Protoberberine and Protopine Skeletons. X-Ray Crystal Structure of 9,10-Dimethoxy-5-methyl-4,5,6,7,12,13-hexahydrothieno[3,2-e][3]benzazeci n-12-one

1988 ◽  
Vol 41 (1) ◽  
pp. 111 ◽  
Author(s):  
JB Bremner ◽  
EJ Browne ◽  
LM Engelhardt ◽  
GS James ◽  
AH White
Keyword(s):  
Molecular Structure ◽  
Cyanogen Bromide ◽  
Methyl Ketone ◽  
Functional Group ◽  
Crystal And Molecular Structure ◽  
Major Product ◽  
Ring System ◽  
X Ray ◽  
A Minor ◽  
Ray Methods

The preparation of the tetracyclic derivatives, (5) and (11), thienanalogues of the tetrahydroprotoberberine alkaloids, is described. Cyanogen bromide-induced water solvolysis of these isomeric compounds proceeded by different routes. 9,10-Dimethoxy-4,7,12,12a- tetrahydro-5H-benzo[g] thieno [3,2-a] quinolizine (11) under these conditions gave as the major product 4-(2-hydroxymethyl-4,5- dimethoxybenzyl )-4,5,6,7-tetrahydrothieno[3,2-c]pyridine-5- carbonitrile (12); no azecino derivatives were detected. By contrast such cleavage of 2,3-dimethoxy-5,8,12,12a-tetrahydro-6H- benzo [a] thieno [3,2-g] quinolizine (5) gave a major solvolytic ring- expanded product, 12-hydroxy-9,10-dimethoxy-4,5,6,7,12,13- hexahydrothieno [3,2-e][3]benzazecine-5-carbonitrile (15), and a minor elimination product, (E)-9,10-dimethoxy-4,5,6,7-tetrahydrothieno[3,2- e][3]benzazecine-5-carbonitrile (16). These last two compounds are examples of a new tricyclic ring system. From functional group interconversions of (15) was derived the N- methyl ketone (18), the first thieno analogue of the protopine alkaloid system. The crystal and molecular structure of this compound, 9,10-dimethoxy-5-methyl-4,5,6,7,12,13-hexahydrothieno[3,2-e][3] benzazecin - 12-one (18), has been determined by single-crystal X-ray methods.

The preparation and rearrangement of some 2,3-oxygenated 2-phenylbornanes

1971 ◽  
Vol 24 (5) ◽  
pp. 1009 ◽  
Author(s):  
JM Coxon ◽  
MP Hartshorn ◽  
AJ Lewis
Keyword(s):  
Thionyl Chloride ◽  
Major Product ◽  
Similar Reaction ◽  
Unsaturated Aldehyde

Reaction of the r-2-hydroxy-2-phenyl-c-3-p-tolylsulphonyloxybornanes (4b) and (10b) with base gave the epimeric 2,3-epoxy-2-phenylbornanes (1) and (2). Acid-catalysed rearrangement of the endo-epoxide (2) gave 2-endo-phenylbornan-3-one (8); similar reaction of the exo-epoxide (1) afforded the unsaturated aldehyde (6) as the major product. Pyrolysis of the cyclic sulphites (16) and (17), prepared from the 2,3-exo-diol (4a) by reaction with thionyl chloride, gave mixtures of 2-endo- phenylbornan-3-one (8) and the aldehyde (5).

The chemistry of lauren-1-ene. V. The structure of an acid-catalysed rearrangement product

1983 ◽  
Vol 36 (12) ◽  
pp. 2581 ◽  
Author(s):  
LR Hanton ◽  
J Simpson ◽  
RT Weavers
Keyword(s):  
Formic Acid ◽  
Major Product ◽  
Rearrangement Product ◽  
X Ray

The major product from the formic-acid-induced rearrangement of lauren-1-ene has been confirmed to be (1S,4S,8R,9S,12R)-4,8,12,14,15-pentamethyltetracyclo[10,3,0,01,9,O4,9]pentadec-14-ene by X-ray analysis of a derived diol.

Sign in / Sign up

Export Citation Format

Share Document