Palladium-catalyzed allylic substitution and cross-coupling reactions have been combined into a sequential procedure to provide a range of disubstituted olefin products starting from two-, three-, and four-carbon common olefin templates. Diverse application of this template strategy is demonstrated in a variety of model studies and in a parallel synthesis (combinatorial) approach to prepare an allylic amine molecular library. An approach toward the preparation of astaxanthin beta-D-diglucoside, an interesting antioxidant whose total synthesis has yet to be reported, using the olefin-template approach is also discussed.

A collection of highly functionalized, trisubstituted olefin building blocks (templates) have been developed for their Pd‐catalyzed elaboration into more complex structures, including natural products and compounds of medicinal chemistry interest. The Pd‐mediated transformations involve a combination of allylic substitution and cross‐coupling reactions. The templates have been designed such that these processes proceed not only with a high degree of regio‐ and stereoselectivity, but the transformations can all be conducted sequentially in the same flask using the same catalyst.

No abstract

Synthesis of Stereodefined Polysubstituted Olefins. Part 1. Sequential Intermolecular Reactions Involving Selective, Stepwise Insertion of Pd(0) into Allylic and Vinylic Halide Bonds. The Stereoselective Synthesis of Disubstituted Olefins. -The selective sequential substitution of special two-(XV), three-(V), (X) or four-carbon olefin templates (I) is presented, which allows for straightforward synthesis of 1,2-disubstituted olefins with controlled double bond geometry. Starting with three-or four-carbon templates, first step usually is a high-yielding palladium-catalyzed allylic substitution or allylic amination, which is followed by various cross-coupling reactions. The reactions can be carried out in a stepwise or, with comparable yields, in a one-pot manner.-(ORGAN, MICHAEL G.; COOPER, JEREMY T.; ROGERS, LAWRENCE R.; SOLEYMANZADEH, FARIBA; PAUL, TIMOTHY; J. Org. Chem. 65 (2000) 23, 7959-7970; Dep. Chem., York Univ., North York, Toronto, Ont. M3J 1P3, Can.; EN)

FINN AND ROGERS-PHENOL-FORMALDEH YDE REACTION 51'(b) Removal of mineral acid used to catalyse a reaction, e.g., hydrolysis of esters, amides or nitriles.(c) Removal ofmineral acid arisingin a reaction (e.g., hydrolysis of a halogenated compound), if necessary continuously, so as to maintain nearly neutral pII.(d) Recovery of valuable organic acids from biological material or fermentadon liquors.(el Recovery of metals, such as chromium or vanadium, after Thc course of thc rcaction bctwccn phenol and formaldehyde has bucn followcd by observing the temperatures at which thc rcaction mixture just becomes turbid. The effect of temperature, dilution with water and methyl alcohol, the concentration and nature of the camlysr on the course of the reaction has bccn observed by this means. The method may also be used to judge nny chosen cnd point of the condcnsation, where only lightly condensed resins are concerned.