24330-55-0Relevant academic research and scientific papers
Synthesis and Liquid Crystal Properties of Dimethylene Linked Compounds Incorporating the Cyclobutane or Spiroheptane Rings
Chan, L. K. M.,Gemmell, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
, p. 229 - 246 (2007/10/02)
The preparation of sixteen dimethylene linked compounds is described heptane ring>, and a comparison is made between the transition temperatures of these compounds and those of the corresponding esters.This comparison once again highlights the fact that the cyclobutane ring should be regarded, in terms of its ability to promote nematic thermal stability, as a "chain stiffener rather than as a ring system.A comparison is also made of the nematic thermal stabilities of the trans-cyclobutane and the spiroheptane systems and of the trans-cyclohexane and the spiroundecane systems.
Synthesis and liquid crystal properties of compounds incorporating cyclobutane, spiroheptane and dispirodecane rings
Chain, L. K. M.,Gemmel, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
, p. 113 - 140 (2007/10/02)
A number of esters of structure (I) incorporating the cyclobutane, spiroheptane, or dispirodecane rings has been prepared using a diethyl malonate synthesis.Strict comparison of the liquid crystal behaviour amongst the three classes containing a terminal cyano-substituent was not possible because both the cyclobutanes and dispirodecanes are mixtures of cis- and trans-isomers; the spiroheptanes are racemic systems.Using preparative hplc, it was however possible to isolate the pure cis- and trans-isomers of two of the cyano-substituted cyclobutane esters (I; R = alkyl, -X- = --, Y = CN).From the physical data and the results for the corresponding spiroheptane esters, conclusions regarding the effects of these ring systems on liquid crystal behaviour were obtained.The pure cis- and trans-isomers of the cyclobutane ester (I, R = C3H7, -X- = --, Y = CN) have been assessed for the trends in both order parameter and viscosity with temperature; the results support the idea that idea that the trans-cyclobutane ring adopts a more planar conformation at higher temperatures.Keywords: cyclobutane- and related spiro-systems, cis-/trans-isomerism, order parameter, briefringence, viscosity, structure/property relations.
STUDY OF THE ANOMERIC EFFECT IN 2-SUBSTITUTED 1,3-DITHIANES
Juaristi, Eusebio,Tapia, Josefina,Mendez, Rodolfo
, p. 1253 - 1264 (2007/10/02)
The conformational analysis of several 2-substituted 1,3-dithianes made possible the evaluation of S-C-Y anomeric interactions, where Y=SCH3,SC6H5,CO2CH3,COC6H5,CO2H and N(CH3)2.The relative magnitude of the effects observed for these groups odithiane(Y)-ΔGocyclohexane(Y)> can be explained in terms of the combined influence of dipole/dipole and two-electron stabilizing interactions (stereoelectronic effect).
Tobacco smoke chemistry. 1. A chemical and mass spectrometric study of tobacco smoke alkyl 2-hydroxy-2-cyclopentenones.
Arnarp,Enzell,Petersson,Pettersson
, p. 839 - 854 (2007/10/02)
A series of alkyl 2-hydroxy-2-cyclopentenones, which comprise biologically and organoleptically active compounds, have been synthesized and subjected to high resolution mass spectrometric studies to clarify structurally significant fragmentation pathways. On the basis of these results, 26 alkyl 2-hydroxy-2-cyclopentenones were identified in the weakly acidic fraction of smoke condensate from American blend type cigarettes, eighteen of which had not been detected in tobacco smoke previously. The utility for identification purposes of the corresponding quinoxaline derivatives, obtained through condensation with o-phenylenediamine, is discussed.
LONG-ACTING CONTRACEPTIVE AGENTS: CYCLOPROPYL AND CYCLOBUTYL ESTERS OF NORETHISTERONE
Shafiee, A.,Vossoghi, M.,Savabi, F.,Vlahov, R.,Tarpanov, V.,et al.
, p. 291 - 308 (2007/10/02)
Several esters of norethisterone (17α-ethynyl-17β-hydroxyestr-4-en-3-one) with carboxylic acids containing a cyclopropyl or cyclobutyl ring have been synthesized and the stereochemistries of the side-chains determined.
Preparation of 15-deoxy-16-hydroxyprostaglandins
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, (2008/06/13)
Analogues of PGE1 having the structural formula, STR1 in which J is R-hydroxymethylene or S-hydroxymethylene; R1 is hydrogen; R2 is hydrogen or together with R4 is a methylene chain of 2 to 3 carbon atoms such that a cycloalkyl of 5 to 6 carbon atoms inclusive is formed; R3 is hydrogen or methyl, or together with R4 is a methylene or a lower alkylated methylene chain of 2 to 5 carbon atoms such that a cycloalkyl or a lower alkylated cycloalkyl of 4 to 7 carbon atoms inclusive is formed, or together with R4 is bicycloalkyl or bicycloalkenyl moiety having the formula: STR2 SUCH THAT A BICYCLOALKYL OR BICYCLOALKENYL COMPOUND IS FORMED, WHEREIN M AND N ARE INTEGERS HAVING A VALUE FROM 0 TO 3, P IS AN INTEGER HAVING A VALUE FROM 0 TO 4 AND Q IS AN INTEGER HAVING A VALUE OF FROM 1 TO 4 AND WHEREIN THE DOUBLE BOND OF SUCH BICYCLOALKENYL IS IN THE M, N, P, OR Q BRIDGE; R4 is hydrogen or methyl or together with R2 or R3 forms a cycloalkyl or bicycloalkyl or bicycloalkenyl as defined above, or together with R5 is a methylene chain of 3 to 5 carbon atoms such that a cycloalkyl of 4 to 6 carbon atoms inclusive is formed; R5 is selected from the group consisting of hydrogen, straight-chain alkyl having from 1 to 3 carbon atoms or together with R4 forms a cycloalkyl as defined above; and R6 is hydrogen or straight-chain alkyl having from 1 to 3 carbon atoms are disclosed. Pge1 ester analogues of the above formula, limited to the structures wherein two of R2, R3 R4 and R5 form a cycloalkyl, lower alkylated cycloalkyl, bicycloalkyl or bicycloalkenyl are also disclosed. The prostaglandin analogues selectively produce bronchodilation and decrease gastric secretion in vivo. Methods of preparing the analogues and starting materials required in the synthesis of the analogues are also disclosed.
