Hydrogen-bonding additives trienes

Cr complexes . This selectivity leads to an interesting preparation of trisubstituted double bonds, such as in a synthesis of citronellol, 31, involving the selective 1,4-hydrogen addition to the conjugated system of triene 32, over tricarbonylchromium methylbenzoate ... 

Beckwith pioneered the use of a Thiol-Oxygen-Co-Oxidation (TOCO) process for the transformation of 1,4-dienes and 1,3,6-trienes to 1,2-dioxolanes [90], As illustrated by the example in Scheme 51 [90a], this process involves phenylthio radical addition to the least substituted double bond, oxygen entrapment, peroxyl radical cyclization, oxygen entrapment and hydrogen atom transfer from the thiol. In accord with the Beckwith-Houk transition state model [91, 92], cyclization provides preferentially the c/s-3,5-disubstituted 1,2-dioxolanes. 

The Pd-carbon bond in the allenylpalladium complex A has reactivity similar to that of bond formed by the oxidative addition of alkenyl haUdes to Pd(0) in the Heck reaction.t lP Smooth insertion of alkenes into the allenylpalladium complexes A and subsequent elimination of /3-hydrogen affords 1,2,4-trienes (Scheme 2). 

Functionalization of the terminal double bond of polyisoprenoids is achieved by regioselective addition of benzenesulphenyl chloride followed by base-induced elimination of hydrogen chloride thus treatment of the benzyl ether (128) of E. E-farnesol gives the sulphide (129) in 48% yield.Trienes and... 

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