Solid-State Structural Investigation of an Organolithium (−)-Sparteine Complex: η3-N-Boc-N-(p-methoxyphenyl)-3-phenylallyllithium⋅(−)-Sparteine

A η ³ monomeric alkyllithium⋅(−)-sparteine complex has been isolated and characterized in the solid state (see picture). Determination of the absolute configuration of this key intermediate in asymmetric metalation/substitution sequences of N-tert-butoxycarbonyl-N-(p-methoxyphenyl)cinnamylamine allows definitive assignment of the stereochemical course of its electrophile-dependent substitution reactions.     

Kinetic resolution of racemic lactones by conjugate additions of allylic organolithium species: direct formation of three contiguous centers with high diastereo- and enantioselectivities

[reaction: see text] Kinetic resolution of racemic alpha,beta-unsaturated lactones by the organolithium species produced from asymmetric lithiation of N-Boc-N-(p-methoxyphenyl)cinnamylamine provides conjugate addition products with three contiguous stereogenic centers in yields of 62-77% with diastereomeric ratios from 75:25 to >99:1 and enantiomeric ratios for the major diastereomers from 94:6 to 98:2.     

Release Behavior of Flavor Encapsulated CD in Slurry Solution Under Boiling Conditions

Cyclodextrin (CD) can control flavor release rate and protect the flavor from volatilization by the formation of inclusion complex with flavor compounds. However, the flavor release rate during cooking, particularly in boiling water has hardly been understood. In this study, flavor release rate of flavor encapsulated CD in slurry or turbid solution under boiling condition was investigated. The release rate constants of methyl caproate and d-limonene depended on the CD concentration, whereas, those of phenyl ethanol hardly did. The plot of a reciprocal number of apparent release rate constant to CD concentration for d-limonene stability constant under boiling condition was obtained. Stability constants for d-limonene in α-CD and β-CD were 185 and 38 M⁻¹, respectively. These stability constants were smaller than the order of 1000 M⁻¹ at room temperature. These results suggested that the addition of CD for protection of flavors in boiling water might have small effect in comparison to that at room temperature. The behavior of flavor release in the boiling water correlated well with the first-order release rate equation, which can be described by the film theory of the interfacial mass transfer.     

Asymmetric synthesis of 4,5,6- and 3,4,5,6-substituted azepanes by a highly diastereoselective and enantioselective lithiation-conjugate addition sequence

Asymmetric syntheses of 4,5,6- and 3,4,5,6-substituted azepanes have been achieved by highly diastereoselective and enantioselective (-)-sparteine-mediated asymmetric lithiation-conjugate additions of N-Boc-N-(p-methoxyphenyl)-2,3-substituted allylamines to a beta-aryl alpha,beta-unsaturated ester followed by hydrolysis, cyclization, and reduction. Access to the enantiomeric adduct is provided by an invertive lithiation-stannylation-lithiation sequence.     

Enantioselective synthesis of 2-substituted 2-phenylethylamines by lithiation-substitution sequences: synthetic development and mechanistic pathway

The lithiation and asymmetric substitution of N-(2-phenylethyl)isobutyramide (2) with selected electrophiles, under the influence of (-)-sparteine, provides benzylically substituted products in 58-90% yields with enantiomeric ratios (ers) from 72:28 to 91:9. Syntheses of enantioenriched dihydroisoquinolines (S)-18 and (S)-19 and a tetrahydroisoquinoline (4S)-20 provide examples of synthetic applications. Mechanistic investigations suggest the enantiodetermining step at -78 degrees C is a dynamic thermodynamic resolution.     

Residual vibration reduction of a flexible beam deploying from a translating hub

This paper presents a method for reducing the residual vibration of a flexible beam deployed from a translating hub. Whereas previous studies have discussed reducing vibration in translating constant-length beams, this study investigates a vibration reduction method for translating beams of variable length. The partial differential equation of motion for a translating beam is derived and transformed into a variational equation. Based on the discretized equations from the variational equation, the dynamic responses of the flexible beam under translation are analyzed. A vibration reduction method is proposed that is effective for both constant- and variable-length deploying translating beams.