Efficient acetalisation of aldehydes catalyzed by titanium tetrachloride in a basic medium
作者:Angelo Clerici、Nadia Pastori、Ombretta Porta
DOI:10.1016/s0040-4020(98)00982-x
日期:1998.12
The acetalisation of aliphatic and aromatic aldehydes is achieved in a basic medium by using catalytic amount of Ti(IV) chloride in MeOH in the presence of NH3 or Et3N. The present protocol shows many advantages over the well known base or acid catalysis: in fact, in contrast to base-promoted acetalisation, aldehydes with electron-rich carbonyl groups react easily, enolizable aldehydes do not undergo
synthesizing the target molecules. The perfect chemoselectivity between aromatic and aliphatic aldehydes is difficult to achieve by the previous methods. The aromatic aldehyde-selective nucleophilic addition in the presence of aliphatic aldehydes was newly accomplished. Namely, the aromatic aldehyde-selective nucleophilic addition using arenes and allyl silanes proceeded in the presence of trialkylsilyl
GEMINI VITAMIN D3 COMPOUNDS AND METHODS OF USE THEREOF
申请人:Adorini Luciano
公开号:US20080280859A1
公开(公告)日:2008-11-13
The invention provides Gemini vitamin D
3
compounds, methods for using the compounds to treat vitamin D3 associated states and pharmaceutical compositions containing the compounds.
Bilobalide is a tetracyclic sesquiterpene containing three contiguous γ-lactone rings and an unusual tert-butyl group, which is found in the leaves of the ginkgo tree (Ginkgo biloba). Three different photochemical approaches towards bilobalide's unique skeleton are presented. A meta photocycloaddition, a [2 + 2] photocycloaddition, and a Paternò–Büchi-reaction were chosen as the respective key steps
Physically mixed catalytic system of amino and sulfo-functional porous organic polymers as efficiently synergistic co-catalysts for one-pot cascade reactions
or alkaline treatment. The bi-functional polymeric materials were utilized as a synergistic catalytic system for one-potcascadereactions including deacetalization–Henry condensation reaction, deacetalization–Knoevenagel condensation reaction and the transformation of 3,4-dihydropyran derivatives to α-ester cyclohexenone compounds. The crosslinked polymeric frameworks effectively isolated sulfonic