scholarly journals Synthesis, structure, and first reactions of a new class of thiacyclophanes

2017 ◽  
Vol 95 (3) ◽  
pp. 278-285 ◽  
Author(s):  
Arunachalam Kannan ◽  
Henning Hopf ◽  
Ina Dix ◽  
Peter G. Jones ◽  
Ludger Ernst
Keyword(s):  
Spectroscopic Data ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
X Ray ◽  
Flash Vacuum Pyrolysis ◽  
New Class ◽  
Product Mixture ◽  
Vacuum Pyrolysis ◽  
Molecular Bridge ◽  
Meta Isomer

In our effort to prepare [m.n]cyclophanes carrying functional groups in their molecular bridges, the thiacyclophanes 14, 19, 20, and 21 have been prepared by simple routes from the pseudo-gem dibromide 10a and the corresponding bis-thiol 10b. The triply-bridged bis-thia-cyclophanes 14, and 19-21 were characterized by their spectroscopic data as well as by X-ray structural analyses. The meta-isomer 20 was oxidized to the bis-sulfone 23, which on flash vacuum pyrolysis (FVP) yielded a product mixture presumably containing the hydrocarbon 26 with a cleaved molecular bridge. Subjecting 23 to Ramberg-Bäcklund conditions (CCl4, NaOH, phase transfer catalysis) provided the chloride 24 in poor yield (9%), a [2.2]paracyclophane in which the new molecular bridge is fully conjugated.

The Pyrolytic Rearrangement of 1-Alkynoyl-3-methylpyrazoles: Synthesis of Pyrazolo[1,5-a]pyridin-5-ols and Related Compounds

1994 ◽  
Vol 47 (6) ◽  
pp. 991 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon ◽  
SC Lee ◽  
RP Mcgeary
Keyword(s):  
Carbon Chain ◽  
Ring Structure ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Fused Ring ◽  
Related Compounds

Flash vacuum pyrolysis of 1-(alkyn-2′-oyl)-3-methylpyrazoles at 650°/0.03 mm forms pyrazolo[1,5-a]pyridin-5-ols, often in high yield, which may bear substituents at C2, C3 or C7. In the absence of a 3-methyl group in the precursor, N-ethynylpyrazoles are formed in low yield. The formation of both types of product is interpreted as involving 3-(N-pyrazolyl)propadienones formed by N1 → N2 migration of the N-alkynoyl group with inversion of the three-carbon chain. The fused-ring structure of 2-methylpyrazolo[1,5-a]pyridin-5-ol (25) was established by X-ray crystallography of the O-benzoyl derivative (27).

A New Class of Tricyclic Diterpenes from Eremophila georgei (Myoporaceae)

1997 ◽  
Vol 50 (7) ◽  
pp. 705 ◽  
Author(s):  
Yana M. Syah ◽  
Emilio L. Ghisalberti ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Spectroscopic Data ◽  
Model Compounds ◽  
X Ray ◽  
New Class ◽  
Relative Stereochemistry

The first example of a new class of tricyclic diterpenes together with two new viscidanes have been isolated from a variety ofEremophila georgei. The structures of the viscidane compounds were assigned on the basis of spectroscopic data and comparison with model compounds. The structure and relative stereochemistry of the lactone (2), which represents a new diterpene skeleton, were established by spectroscopic and X-ray crystallographic methods. The derivation of (2) from a viscidane is suggested.

The chemistry of Eremophila spp. XVIII. A new class of diterpenes from Eremophila viscida

1983 ◽  
Vol 36 (5) ◽  
pp. 993 ◽  
Author(s):  
EL Ghisalberti ◽  
CH Hocart ◽  
PR Jefferies ◽  
GM Proudfoot ◽  
BW Skelton ◽  
...  
Keyword(s):  
Spectroscopic Data ◽  
Crystallographic Analysis ◽  
X Ray ◽  
New Class

Two new diterpenes have been isolated from the resin of E. viscida Endl. Evidence for their structure was obtained from spectroscopic data and from X-ray crystallographic analysis which show them to be members of a new class of diterpenes containing a C 5 extended acorane skeleton.

Unexpected Pyrolytic Behaviour of Substituted Benzo[c]thiopyran and Thieno[2,3-c]thiopyran S,S-dioxides

2014 ◽  
Vol 67 (9) ◽  
pp. 1288 ◽  
Author(s):  
R. Alan Aitken ◽  
Clémence Hauduc ◽  
M. Selim Hossain ◽  
Emily McHale ◽  
Adrian L. Schwan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ring Expansion ◽  
Hydrogen Atom Transfer ◽  
Membered Ring ◽  
X Ray ◽  
Flash Vacuum Pyrolysis ◽  
Vacuum Pyrolysis ◽  
Higher Temperature ◽  
Intramolecular Hydrogen ◽  
Carbonyl Products

Flash vacuum pyrolysis (FVP) of benzo[c]thiopyran S,S-dioxide (1) results in formation of indene and 2-vinylbenzaldehyde as previously described. A range of eight analogues with various substitution patterns are found to behave differently. In general, there is no extrusion of SO2 to give products analogous to indene, but unsaturated carbonyl products analogous to 2-vinylbenzaldehyde are formed in most cases by way of ring expansion to a 7-membered ring sultine, extrusion of SO, and intramolecular hydrogen atom transfer. Other processes observed include formation of anthracene via an isomeric 7-membered sultine with loss of SO, CO and methane or butane, and formation of 4-ethylidene-4,5-dihydrocyclobuta[b]thiophenes by way of SO loss, a radical rearrangement, and extrusion of acetone. The analogues with a halogen substituent at position 8 on the benzene ring require a higher temperature to react and give naphthalene resulting from net elimination of HX and SO2. The X-ray crystal structure of 1 is also reported.

The Reaction of Thiophene 1,1-Dioxide With Haloform-Sodium Hydroxide Under Phase-Transfer Catalysis

1989 ◽  
Vol 42 (8) ◽  
pp. 1307 ◽  
Author(s):  
BR Dent ◽  
GJ Gainsford
Keyword(s):  
Low Temperature ◽  
Sodium Hydroxide ◽  
Good Yield ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Structural Data ◽  
X Ray ◽  
Benzyltriethylammonium Chloride

3,4-Dibromotetrahydrothiophen 1,1-dioxide (2) reacts in the reagent system chloroformaqueous sodium hydroxide-benzyltriethylammonium chloride to give 3-dichloromethylene-2,3-dihydrothiophen 1,1-dioxide (6a), for which low-temperature X-ray structural data are presented. Bromoform may be substituted for chloroform to give the corresponding dibromomethylene compound (6b) in good yield.

Synthesis of 1,8,8-Trimethyl-6,10-dioxaspiro[4.5]dec-2-ene-1-ethanol; X-Ray Crystallography of (1RS,2SR)-1,8,8-Trimethyl-1-(prop-2'-enyl)-6,10-dioxaspiro[4.5]dec-2-yl Benzoate

1994 ◽  
Vol 47 (4) ◽  
pp. 739 ◽  
Author(s):  
DJ Collins ◽  
GD Fallon ◽  
RP Mcgeary
Keyword(s):  
Oxidative Cleavage ◽  
Quantitative Yield ◽  
Borohydride Reduction ◽  
X Ray ◽  
X Ray Crystallography ◽  
Flash Vacuum Pyrolysis ◽  
Hydride Reduction ◽  
Tetrabutylammonium Fluoride ◽  
Vacuum Pyrolysis ◽  
Relative Stereochemistry

Reaction of 2-methyl-2-(prop-2′-enyl)cyclopentane-1,3-dione (2) with 2,2-dimethylpropane-1,3-diol gave 1,8,8-trimethyl-1-(prop-2′-enyl)-6,10-dioxaspiro[4.5]decan-2-one (3), hydride reduction of which afforded a 1:1 epimeric mixture of the corresponding alcohols (4a) and (4b). They were separated, and the derived benzoates (5a) and (5b) were each subjected to a three-step sequence of oxidative cleavage, borohydride reduction and silylation to give the pure epimers (8a) and (8b) of 1,8,8-trimethyl-1-(2′-t-butyldimethylsilyloxyethyl)-6,10-dioxaspiro[4.5]dec-2-yl benzoate. Flash vacuum pyrolysis of a mixture of these epimeric benzoates (8a,b) gave an almost quantitative yield of 1,8,8-trimethyl-1-(2′-t-butyldimethylsilyloxyethyl)-6,10-dioxaspiro[4.5]dec-2-ene (9a), treatment of which with tetrabutylammonium fluoride afforded the corresponding alcohol (9b). The relative stereochemistry of (1RS,2SR)-1,8,8-trimethyl-1-(prop-2′-enyl)-6,10-dioxaspiro [4.5]dec-2-yl benzoate (5b) was established by X-ray crystallography.

Synthesis, structure and application of a new class of Tr-podands derived in phase-transfer catalysis

2008 ◽  
Vol 287 (1-2) ◽  
pp. 165-170 ◽  
Author(s):  
Bogusława Łęska ◽  
Radosław Pankiewicz ◽  
Błażej Gierczyk ◽  
Grzegorz Schroeder
Keyword(s):  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
New Class
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