Synthesis and transformations of alkyl N-(1-cyclohex-3-enyl)carbamates prepared from cyclohex-3-ene carboxylic acid via Curtius rearrangement

The Curtius rearrangement of cyclohex-3-ene carboxylic acid using diphenylphosphoryl azide in the presence of triethylamime and ethanol, t-butanol or benzyl alcohol has been described. As a result the synthesis of ethyl, t-butyl or benzyl N-(1-cyclohex-3-enyl)carbamates has been achieved in one pot, in good chemical yield. A series of transformations of benzyl N-(1-cyclohex-3-enyl)carbamate, such as iodination and epoxidation, as well as opening of the corresponding ring epoxide, have been carried out leading to some useful oxygenated cyclohexylamimo building blocks.     

A High Yielding, One-Pot, Triton-B Catalyzed, Expeditious Synthesis of Carbamate Esters by Four Component Coupling Methodology

Summary. A novel process for the one-step chemoselective conversion of alkyl halides into carbamates as protected amines was developed using benzyltrimethylammonium hydroxide (Triton-B) in presence of gaseous carbon dioxide. Thus, carbamate esters of different amines were prepared in very good to excellent yields. Present address: Institute of Organic and Biomolecular Chemistry, George–August University, 37077, G?ttingen, Germany     

Quantitative aqueous attenuated total reflectance Fourier transform infrared spectroscopy : Part II. Integrated molar absorptivities of alkyl carboxylates

A quantitative attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopic method is developed for the analysis of total carboxylate concentration, [COO⁻], in aqueous solution. The short (12–13 μm) and highly reproducible pathlength of the ATR cell permits quantitative subtraction of the water peak at 1640 cm⁻¹. Carboxylate quantitation is based on the area of the asymmetric stretching peak, which is nearly independent of compound structure. The molar absorptivity of alkyl carboxylates in water is 438 ± 58 l mol⁻¹ cm⁻¹, and the integrated molar absorptivity is 2.95 ± 0.08 × 10⁴ l mol⁻¹ cm⁻² (n = 15 compounds, 0.1 M ≤ [COO⁻] ≤ 1.5 M). The [COO⁻] in solutions of mixed carboxylates is measured with a root mean square error of 2.4% and a small (+1.5) positive bias. The accuracy of the method is limited by the assumption that integrated absorbance is constant for all COO⁻ groups.     

2,5-二甲氧基苯基烷基酮与t-BuMgCl反应的机理研究

2,5-二甲氧基苯基烷基酮1_(a-d)(烷基分别为甲基、乙基、异丙基和叔丁基)与t-BuMgCl反应后,主要生成了1,2-加成产物、1.6-共轭加成产物及还原产物,产物及其分布在不同程度上受酮的结构、反应介质以及金属镁中过渡金属杂质的含量等因素的影响。据此,提出了反应的可能机理。     

An atom-efficient palladium-catalyzed cross-coupling reaction of triarylbismuths with acid chlorides: synthesis of diaryl and alkyl aryl ketones

The cross-coupling reaction of triarylbismuths with acid chlorides using a catalytic amount of PdCl₂/PPh₃ afforded the corresponding ketones in high yields. The reactions of aromatic and aliphatic acid chlorides occurred with atom efficiency, as 3 equiv of acid chlorides coupled effectively with 1 equiv of triarylbismuths to yield 3 equiv of the corresponding diaryl and alkyl aryl ketones.     

Alkyl phosphines promoted reductive coupling of acyl cyanides: formation of O-acyl cyanohydrins

The reductive coupling of acyl cyanides promoted by alkyl phosphines has been discovered. Under mild reaction conditions, the substituted cyanohydrins were obtained in moderate to high yields by using trimethylphosphine or tributylphosphine as a promoter. The possible mechanism involved in the reaction was discussed on the basis of deuterium labeling and control experiments, indicating that one hydride transfer took place from alkyl phosphine to O-acyl cyanohydrin.     

二烷基二硫代磷酸锌的大气压化学电离质谱

采用大气压化学电离质谱技术（APCI－MS）对润滑油抗氧抗腐蚀添加剂丁基、辛基混合烷基硫代磷酸锌进行了分析，并结合APCI－MS技术中特有的源内化学电离检测（CID）功能对二辛基二硫代磷酸锌进行了结构表征；该法简便、快速，与传统方法相比有优越之处。     

A Microcalorimetric Study of Host–Guest Complexes of α-Cyclodextrin with Alkyl Trimethyl Ammonium Bromides in Aqueous Solutions

Interactions between α-CD and three alkyl trimethyl ammonium bromides, a homologues series of surfactants, in aqueous solutions have been investigated with titration microcalorimetry at 298.15 K. The results are discussed in the light of the amphiphilic interaction and the iceberg structure of water molecules existing around the hydrophobic tail of the surfactant. The stoichiometry of the host–guest complex changes from 1:1 to 2:1, as the number of carbon atoms (n) in the hydrophobic chain, C_nH_2n+1, increases from 8 to 14. All the complexes are quite stable, with the apparent experiential stability constants being β₁ = 2.65 × 10³ dm³-mol⁻¹, β₂ = 4.85 × 10⁶ dm⁶-mol⁻², β₂ = 6.50 × 10⁶ dm⁶-mol⁻², respectively for n = 8, 12, 14. All the complexation processes are shown to be enthalpy driven, and the standard enthalpy effect (−ΔH⁰) increases while standard entropy change (ΔS⁰) decreases with elongation of the hydrophobic chain.     

乙烯基单体正离子聚合中链增长速率常数的研究进展

碳正离子聚合中,聚合速率常数的测定方法通常包括电导法、绝热量热法、胺抑制法、止流光谱法及扩散计时法。在烷基乙烯基醚、苯乙烯及其衍生物和异丁烯等几种常见乙烯基单体的正离子聚合中,本文介绍不同测定方法得到的不同结构碳正离子(包括自由离子和离子对)的链增长速率常数(kp 和kp±)。     

Neue Synthesemethoden, 11. Mitt. α-Alkylthiolierung von cyclischen Ketonen via ihre Enamine

Enamines of cyclic ketones were -alkylthiolated in good yields by simply refluxing them with alkyl 4-methylbenzenethiosulfonates and triethylamine in acetonitrile.