The (polyenoyl)tetramicacid militarinone C (1) heads a family of seven members. Before our work, the configuration of C-5 was unknown whereas the configurations of C-8′ and C-10′ were either (R,R) or (S,S). We synthesized the four stereoisomers of constitution 1, which conform with these insights. This included cross-coupling both enantiomers of the western building block (8) with both enantiomers
LIQUID CRYSTAL COMPOUND HAVING NEGATIVE DIELECTRIC ANISOTROPY, LIQUID CRYSTAL COMPOSITION, AND LIQUID CRYSTAL DISPLAY DEVICE
申请人:MASUKAWA TOKIFUMI
公开号:US20090278088A1
公开(公告)日:2009-11-12
A liquid crystal compound is provided that has excellent characteristics, such as a negatively large dielectric anisotropy. A liquid crystal composition containing the compound, and a liquid crystal display device containing the composition are also provided. A compound having the three factors, i.e., (1) a tetrahydropyran ring, (2) —CH
2
O— or —OCH
2
— and (3)
exhibits excellent characteristics including a negatively large dielectric anisotropy. The use of the compound having the characteristics provides an excellent liquid crystal composition and an excellent liquid crystal display device.
Nuclear magnetic resonance and infrared spectra of some aldimines (azomethines)
作者:K. A. W. Parry、P. J. Robinson、P. J. Sainsbury、M. J. Waller
DOI:10.1039/j29700000700
日期:——
N.m.r. and i.r. spectra are reported for 19 imines of the type PC[graphic omitted]N–C[graphic omitted]QR (P = alkyl or aryl and Q, R =(H,alk), (alk,alk), or –[CH2]n–). The variation in |Jab| with structure is examined, and evidence is found for conformational effects similar to those for allylic coupling. The CN stretching frequencies fall into characteristic and separate ranges for P = alkyl and P
报告了19种亚胺PC [Graphic] N–C [Graphic] QR(P =烷基或芳基和Q,R =(H,alk),(alk,alk)或– [CH 2 ] n –)。|中的变化 J ab | 研究了具有结构的结构,并发现了构象效应与烯丙基偶联相似的证据。对于P =烷基和P =芳基,C N的拉伸频率落入特征和单独的范围,但是较好的效果通常并不明显。
Total Synthesis of (±)-Deoxypenostatin A. Approaches to the Syntheses of Penostatins A and B
作者:Barry B. Snider、Tao Liu
DOI:10.1021/jo000850x
日期:2000.12.1
A short synthesis of (+/-)-deoxypenostatin A (28) has been carried out using the convergent coupling of dienal 11, epoxide 13, and methylenetriphenylphosphorane (17) to prepare trienol 19 in only two steps. The key step is the Yb(OTf)(3)-catalyzed intramolecular Diels-Alder reaction of hydrated trienyl glyoxylate 23, which gives lactone 24 stereoselectively. Elaboration of lactone 24 to enone 27 by
Stereocontrolled synthesis of E-homoallylic sulfides with 1,4,5 related chiral centres using the [2,3] sigmatropic rearrangement of sulfonium ylides
作者:Richard C. Hartley、Ian C. Richards、Stuart Warren
DOI:10.1039/p19960000359
日期:——
An aldol condensation sets up the stereochemistry. Lactonisation with 1,2 arylsulfanyl migration followed by reduction and sulfur-assisted dehydration converts the aldols stereospecifically into allylic sulfides with 1,2 related chiral centres. Sulfonium salts are generated from the allylic sulfides at low temperature, and are deprotonated to give sulfoniumylides which undergo [2,3] sigmatropic rearrangement