Some studies on the solvolysis of 1-chloro-1-alkyl cycloalkanes

1980 ◽  
Vol 58 (14) ◽  
pp. 1484-1489 ◽  
Author(s):  
K. Ranganayakulu ◽  
M. Vasumathi Devi ◽  
R. Balaji Rao ◽  
K. Rajeswari
Keyword(s):  
Activation Energy ◽  
Chair Conformation ◽  
Ring System ◽  
Membered Ring ◽  
Energy Contribution ◽  
Ring Systems ◽  
Chair Form ◽  
Carbonium Ion ◽  
Rearrangement Reaction ◽  
Twist Boat

The effect of the bulk of the sidechain on the rate of solvolysis of 1-alkyl cyclopentyl, cyclohexyl, and cycloheptyl chlorides has been studied. With the exception of the t-butyl systems, the ratio of solvolysis rates for the three ring systems falls in a given series. The slower rate of solvolysis in the six-membered ring system may be due to an extra activation energy contribution caused by the conversion of a neutral chair form to the twist boat or half chair conformation, prior to the actual solvolysis. In the case of five- and seven-membered ring systems the formation of an intermediate carbonium ion is sterically favoured (I-strain or eclipsing interaction) consistent with earlier findings. The faster rate of solvolysis of 1-t-butylcycloalkyl chlorides is likely due to a rearrangement reaction where alkyl participation enhances the rate of solvolysis.

scholarly journals Crystal structure of (E)-13-(pyrimidin-5-yl)parthenolide

2015 ◽  
Vol 71 (12) ◽  
pp. 1536-1538 ◽  
Author(s):  
Shobanbabu Bommagani ◽  
Narsimha R. Penthala ◽  
Sean Parkin ◽  
Peter A. Crooks
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Heck Reaction ◽  
Lactone Ring ◽  
Chair Conformation ◽  
Ring System ◽  
Membered Ring ◽  
Reaction Conditions ◽  
Compound C ◽  
Pyrimidine Moiety

The title compound, C19H22N2O3, {systematic name (1aR,4E,7aS,8E,10aS,10bR)-1a,5-dimethyl-8-[(pyrimidin-5-yl)methylidene]-2,3,6,7,7a,8,10a,10b-octahydrooxireno[2′,3′:9,10]cyclodeca[1,2-b]furan-9(1aH)-one} was obtained from the reaction of parthenolide [systematic name (1aR,7aS,10aS,10bR,E)-1a,5-dimethyl-8-methylene-2,3,6,7,7a,8,10a,10b-octahydrooxireno[2′,3′:9,10]cyclodeca[1,2-b]furan-9(1aH)-one] with 5-bromopyrimidine under Heck reaction conditions, and was identified as anEisomer. The molecule possesses ten-, five- (lactone) and three-membered (epoxide) rings with a pyrimidine group as a substituent. The ten-membered ring displays an approximate chair–chair conformation, while the lactone ring shows a flattened envelope-type conformation. The dihedral angle between the pyrimidine moiety and the lactone ring system is 29.43 (7)°.

scholarly journals Crystal structure of 2-amino-N-(2-fluorophenyl)-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxamide

2015 ◽  
Vol 71 (11) ◽  
pp. o807-o808
Author(s):  
K. Chandra Kumar ◽  
V. Umesh ◽  
T. K. Madhura ◽  
B. M. Rajesh ◽  
Chandra
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Molecular Conformation ◽  
Chair Conformation ◽  
Ring System ◽  
Membered Ring ◽  
Compound C

In the title compound, C15H15FN2OS, the dihedral angle between the planes of the benzothiophene ring system and the fluorobenzene ring is 3.74 (14)°. The six-membered ring of the benzothiophene moiety adopts a half-chair conformation. The molecular conformation is consolidated by intramolecular N—H...F and N—H...O hydrogen bonds. In the crystal, molecules are linked by N—H...O hydrogen bonds, generatingC(6) [001] chains.

scholarly journals Crystal structure of (1S,2R,4R,9S,11S,12R)-9α-hydroxy-4,8-dimethyl-12-[(thiomorpholin-4-yl)methyl]-3,14-dioxatricyclo[9.3.0.02,4]tetradec-7-en-13-one

2015 ◽  
Vol 71 (2) ◽  
pp. o140-o141
Author(s):  
Ahmed Benharref ◽  
Mohamed Akssira ◽  
Lahcen El Ammari ◽  
Mohamed Saadi ◽  
Moha Berraho
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Chair Conformation ◽  
Chloroform Extract ◽  
Ring System ◽  
Membered Ring ◽  
Epoxy Ring ◽  
Aerial Parts ◽  
Compound C ◽  
Hydrogen Bonding Interactions

The title compound, C19H29NO4S, was synthesised from 9α-hydroxyparthenolide (9α-hydroxy-4,8-dimethyl-12-methylene-3,14-dioxatricyclo[9.3.0.02,4]tetradec-7-en-13-one), which was isolated from the chloroform extract of the aerial parts of the plantAnvillea radiata. The molecule is built up from two fused five- and ten-membered rings, with an additional epoxy ring system and a thiomorpholine group as a substituent. The ten-membered ring adopts an approximate chair–chair conformation, while the thiomorpholine ring displays a chair conformation and the five-membered ring has an envelope conformation, with the C atom closest to the hydroxy group forming the flap. An intramolecular O—H...N hydrogen bond closes anS(8) ring. The crystal structure features weak C—H...O hydrogen-bonding interactions, which link the molecules into [010] chains.

Photosolvolysis of Bridgehead Quaternary Ammonium Salts. III. Synthesis of Some 3-Benzazecine, 1H-2,6-Benzoxazecine and 2H-3,6-Benzoxazecine Derivatives and a 2H-1,4-Oxazocine Derivative

1985 ◽  
Vol 38 (11) ◽  
pp. 1591 ◽  
Author(s):  
JB Bremner ◽  
KN Winzenberg
Keyword(s):  
Chloroform Solution ◽  
Chair Conformation ◽  
Ring System ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
High Yield ◽  
Methyl Derivative ◽  
Isoquinolinium Salt ◽  
Cis And Trans ◽  
Twist Boat

Photosolvolysis of a mixture of cis - and trans-9,10-dimethoxy-5-methyl- 1,3,4,6,7,11b-hexahydro-2H-benzo[a] quinolizinium iodide (2) in methanol gave, after workup, a very low yield of 8,10,11-trimethoxy-3-methyl- 1,2,3,4,5,6,7,8-octahydro-3-benzazecine (3a). Similarly 1,10,11 trimethoxy-6-methyl-3,4,5,6,7,8-hexahydro-1H-2,6-benzoxazecine (8a) and 1,10,11-trimethoxy-6-methyl-1,4,5,6,7,8-hexahydro-2H-3,6-benzoxazecine (16a) were obtained in fair and low yields respectively from the N- methyl tetrahydro-2H,6H-[1,3] oxazino [2,3-a] isoquinolinium (7a) and hexahydro [1,4] oxazino [3,4-a] isoquinolinium (15) iodide precursors; a 1- methyl derivative (8b) of (8a) was also prepared. The ring-opened products 3-[N-2-{(4,5-dimethoxy-2-dimethoxymethyl)-phenyl}ethyl-N-methyl]aminopropan-1-ol (9a) and 3-[N-2-{(4,5-dimethoxy-2-1′,1′- dimethoxyethyl )-phenyl}ethyl-N-methyl]aminopropan-1-ol (9b) were also obtained from the [1,3] oxazino [2,3-a]- isoquinolinium salt derivatives. Photolysis of (2) and 9,10-dimethoxy-5-methyl-1,3,4,6,7,11b-hexa-hydro[1,4] oxazino [3,4-a] isoquinolinium iodide (15) in acidified aqueous solution afforded, after workup, the benzazecin-8-ol (3b) and hexahydro-2H-3,6-benzoxazecin-1-ol (16b) products respectively, but again in very low yield. Some mechanistic rationalizations of these results are given.Photosolvolysis of 7a-(3,4-dimethoxy)phenyl-4-methyl-2,3,5,6,7,7a- hexahydropyrrolo [2,1-b] oxa-zolium iodide (22) in methanol afforded a high yield of 8-methoxy-4-methyl-8-(3,4-dimethoxy)-phenyl-3,4,5,6,7,8- hexahydro-2H-1,4-oxazocine (24) in a new ring-destruction approach to this ring system. From 13C n.m.r . data, the twist-boat-chair conformation was tentatively assigned to (24) in (D)chloroform solution.

scholarly journals Crystal structures of ethyl (2S*,2′R*)-1′-methyl-2′′,3-dioxo-2,3-dihydrodispiro[1-benzothiophene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxylate and ethyl (2S*,2′R*)-5′′-chloro-1′-methyl-2′′,3-dioxo-2,3-dihydrodispiro[1-benzothiophene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxylate

2014 ◽  
Vol 70 (8) ◽  
pp. 94-97 ◽  
Author(s):  
M. P. Savithri ◽  
M. Suresh ◽  
R. Raghunathan ◽  
G. Vimala ◽  
R. Raja ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Dihedral Angle ◽  
Ring System ◽  
Membered Ring ◽  
Equatorial Position ◽  
Ring Systems ◽  
Envelope Conformation ◽  
Extended Conformation ◽  
The Mean

In the title compounds, C22H20N2O4S, (I), and C22H19ClN2O4S, (II), the pyrrolidine rings have twist conformations on the spiro–spiro C—C bonds. In (I), the five-membered ring of the oxindole moiety has an envelope conformation with the spiro C atom as the flap, while in (II) this ring is flat (r.m.s. deviation = 0.042 Å). The mean planes of the pyrrolidine rings are inclined to the mean planes of the indole units [r.m.s deviations = 0.073 and 0.069 Å for (I) and (II), respectively] and the benzothiophene ring systems (r.m.s. deviations = 0.019 and 0.034 Å for (I) and (II), respectively) by 79.57 (8) and 88.61 (7)° for (I), and by 81.99 (10) and 88.79 (10)° for (II). In both compounds, the ethoxycarbonyl group occupies an equatorial position with an extended conformation. The overall conformation of the two molecules differs in the angle of inclination of the indole unit with respect to the benzothiophene ring system, with a dihedral angle between the planes of 71.59 (5) in (I) and 82.27 (7)° in (II). In the crystal of (I), molecules are linkedviapairs of N—H...O hydrogen bonds, forming inversion dimers enclosingR22(14) loops. The dimers are linkedviaC—H...O and bifurcated C—H...O(O) hydrogen bonds, forming sheets lying parallel to (100). In the crystal of (II), molecules are again linkedviapairs of N—H...O hydrogen bonds, forming inversion dimers but enclosing smallerR22(8) loops. Here, the dimers are linked by C—H...O hydrogen bonds, forming ribbons propagating along [010].

scholarly journals Crystal structure of (1S,3R,8R,9R,10S)-2,4,6-tris(2,2-dichloro-3,7,7,10-tetramethyltricyclo[6.4.0.01,3]dodec-9-yl)cyclotriboroxane

2015 ◽  
Vol 71 (8) ◽  
pp. 941-943
Author(s):  
Ahmed Benharref ◽  
Lahcen El Ammari ◽  
Mohamed Saadi ◽  
Noureddine Mazoir ◽  
Moha Berraho
Keyword(s):  
Crystal Packing ◽  
Membered Ring ◽  
Van Der Waals Interactions ◽  
Maximum Deviation ◽  
Boat Conformation ◽  
Ring Systems ◽  
Compound C ◽  
Fused Ring ◽  
The Mean ◽  
Twist Boat

The title compound, C48H75B3Cl6O3, was synthesized in two steps from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The molecule consists of an almost planar cyclotriboroxane ring [maximum deviation = 0.036 (2) Å] linked to three identical fused ring systems with different conformations. Each of the three attached ring systems is built up from a seven-membered ring to which a six- and a three-membered ring are fused. The three six-membered rings have a twist-boat conformation, whereas the seven-membered rings display boat, chair and twist-boat conformations. The dihedral angles between the central boroxane ring and the mean planes of the attached six-membered rings are 63.67 (18), 54.89 (2) and 56.57 (19)°. The crystal packing is governed only by van der Waals interactions.

Synthesis and conformations of α-aminoadipyl- and glycyl-α-aminoadipylthiazepine sulfoxides

1981 ◽  
Vol 59 (2) ◽  
pp. 406-421 ◽  
Author(s):  
Saul Wolfe ◽  
Raymond John Bowers ◽  
Syed Khaqan Hasan ◽  
Peter Michael Kazmaier
Keyword(s):  
Hydrogen Bond ◽  
Carbon Atom ◽  
Formic Acid ◽  
Chair Conformation ◽  
Membered Ring ◽  
Amide Proton ◽  
Penicillin Biosynthesis ◽  
Boat Conformation ◽  
Internal Hydrogen Bond ◽  
Twist Boat

The title compounds, having the R-absolute configurations at sulfur, and labelled with 14C at carbons 5, 6, and 7 of the seven-membered ring, have been synthesized by condensation of isotopically labelled 3D-benzhydryloxycarbonyl-6L-amino-2,2-dimethyl-5-oxoperhydro-1,4-thiazepine with N-Boc- and α-benzhydryl-protected L-α-aminoadipic acid and glycyl-L-α-aminoadipic acid, followed by oxidation with m-chloroperoxybenzoic acid and complete deprotection with formic acid. The conformations of the sulfoxides, and related thiazepines and thiazepine sulfoxides, have been examined by 1Hmr spectroscopy. All thiazepines, and the two title sulfoxides, appear to exist in a twist boat conformation. Most other sulfoxides exist in a chair conformation, which is stabilized by an internal hydrogen bond between the sulfinyl oxygen and the amide proton at C6; when this hydrogen bond is not present, both chair and twist boat conformations may be observable. The title compounds are of interest as possible intermediates in penicillin biosynthesis from glycyl-δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine (GACV) or ACV, according to a new theory, which deals, in particular, with the stereochemical course of the biosynthesis at the beta (β) carbon atom of valine.

scholarly journals 12-{[4-(4-Bromophenyl)piperazin-1-yl]methyl}-9α-hydroxy-4,8-dimethyl-3,14-dioxatricyclo[9.3.0.02,4]tetradec-7-en-13-one

2014 ◽  
Vol 70 (4) ◽  
pp. o497-o498 ◽  
Author(s):  
Mohamed Loubidi ◽  
Ahmed Benharref ◽  
Lahcen El Ammari ◽  
Mohamed Saadi ◽  
Moha Berraho
Keyword(s):  
Molecular Conformation ◽  
Crystal Packing ◽  
Chair Conformation ◽  
Chloroform Extract ◽  
Ring System ◽  
Membered Ring ◽  
Epoxy Ring ◽  
Piperazine Ring ◽  
Aerial Parts ◽  
Compound C

The title compound, C25H33BrN2O4, was synthesized from 9α-hydroxyparthenolide (9α-hydroxy-4,8-dimethyl-12-methylen-3,14-dioxa-tricyclo[9.3.0.02,4]tetradec-7-en-13-one), which was isolated from the chloroform extract of the aerial parts ofAnvillea radiata. The molecule is built up from two fused five- and ten-membered rings with an additional epoxy ring system and a bromophenylpiperazine group as a substituent. The ten-membered ring adopts an approximate chair–chair–chair conformation, while the piperazine ring displays a chair conformation and the five-membered ring shows an envelope conformation with the C atom closest to the hydroxy group forming the flap. An intramolecular O—H...N hydrogen bond stabilizes the molecular conformation. The crystal packing features C—H...O hydrogen bonds, which link the molecules into zigzag chains running along theb-axis direction.

scholarly journals Crystal structure of 16-hydroxy-4,4,10,13,14-pentamethyl-17-(6-methylhept-5-en-2-yl)-4,5,6,9,10,11,12,13,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3(2H)-one

2015 ◽  
Vol 71 (7) ◽  
pp. o464-o465 ◽  
Author(s):  
Jun-Jun Ge ◽  
Pian Chen ◽  
Xiao-Xia Ye
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Chair Conformation ◽  
Membered Ring ◽  
Boat Conformation ◽  
Carbonyl Groups ◽  
Compound C ◽  
Cyclohexene Ring ◽  
Supramolecular Chains ◽  
Twist Boat

The title compound, C30H48O2, contains a fused four-ring triterpenoid system. In the molecule, the two cyclohexane rings adopt a chair conformation and a twist boat conformation, respectively, the central cyclohexene ring adopts a half-chair conformation whereas the five membered ring adopts an envelope conformation. In the crystal, O—H...O hydrogen bonds between the hydroxy and carbonyl groups of adjacent molecules link the molecules into supramolecular chains propagating along theb-axis direction.

scholarly journals Crystal structure of ethyl 5′′-fluoro-2′′,3-dioxo-6′,7′,8′,8a'-tetrahydro-2′H,3H,5′H-dispiro[benzo[b]thiophene-2,1′-indolizine-3′,3′′-indoline]-2′-carboxylate

2015 ◽  
Vol 71 (3) ◽  
pp. o156-o157 ◽  
Author(s):  
R. Raja ◽  
J. Govindaraj ◽  
M. Suresh ◽  
R. Raghunathan ◽  
A. SubbiahPandi
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Chair Conformation ◽  
Ring System ◽  
Membered Ring ◽  
Piperidine Ring ◽  
Pyrrolidine Ring ◽  
Compound C ◽  
The Mean ◽  
Ring Motif

In the title compound, C25H23FN2O4S, the fused piperidine ring of the octahydroindolizine ring system adopts a chair conformation and the five-membered ring has a twisted conformation on the N—C(spiro) bond. The mean planes of the benzothiophene and indoline ring systems are inclined to the mean plane of the pyrrolidine ring by 83.1 (1) and 84.9 (1)°, respectively, and to each other by 29.37 (17)°. In the crystal, molecules are linkedviapairs of N—H...O hydrogen bonds, forming inversion dimers with anR22(8) ring motif. The dimers are linkedviaC—H...O hydrogen bonds, forming slabs lying parallel to (100). The packing between the slabs features a short [2.734 (2) Å] F...F contact.

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