Tetrahedron

Stereoselectivity of esterification reaction of some allylic alcohols, mainly unsaturated pyranosides, with benzoic acid in the presence of diethyl azodicarboxylate and triphenyl phosphine was investigated. The reaction was found to proceed with inversion, without allylic rearrangement.

The stereocontrolled synthesis of β-galactosyl-5-aza-sphinganines was accomplished with high efficiency by a novel and convergent strategy. The truncated β-galactosphinganine 5 was easily acylated with different long chains. Moreover, the simple conversion of thiazole to formyl enabled 5-aza-alkylchains to be introduced via an amino-reduction reaction. The overall yield for the synthesis of β-galacto-5-aza-sphinganines 9 and 13 was about 30–35% starting from

The utilization of ultrasound radiation in the Baylis–Hillman reaction with several aldehydes (aromatics and aliphatics) and different α,β-unsaturated reactants is described. For all aldehydes tested, the utilization of ultrasound sources augmented the reaction rate and the chemical yields. The use of ultrasound with two different catalysts (tri-n-butylphosphine and 1,4-diazabicyclo[2.2.2]octane [DABCO]) was also investigated. It was clearly demonstrated that DABCO is much more effective for catalyzing a Baylis–Hillman reaction under the influence of ultrasound than is tri-n-butylphosphine. No effect on reaction rate was observed when the concentration of DABCO was increased.The scope of the utilization of ultrasound radiation in the Baylis–Hillman reaction with several aldehydes (substituted aromatics and aliphatics) is described. For all aldehydes tested, the use of ultrasound sources augmented the reaction rate and the chemical yields. Ultrasound radiation is also compatible with...

A complete set of platinum(II) solketal substituted phthalocyanines has been synthesized and characterized. To evaluate their potential as Type II photosensitizers for photodynamic therapy, comparative studies of their photophysical and photochemical properties with analogous zinc(II) series have been achieved: electronic absorption, fluorescence quantum yields, lifetimes, and fluorescence quenching by benzoquinone, as well as singlet oxygen generation and photodegradation. It appears that platinum(II) phthalocyanines are worth being used as Type II photosensitizers, as they exhibit good singlet oxygen generation and appropriate photodegradation.

Silylcupration of allene using phenyldimethylsilylcopper or t-butyldiphenylsilylcopper followed by reaction with α,β-unsaturated acyl chlorides, aldehydes or ketones affords allylsilane-containing divinyl ketones and oxoallylsilanes, respectively. They undergo highly stereocontrolled silicon-assisted intramolecular cyclizations when treated with protic or Lewis acid leading to cyclopentane ring-formation.