Nucleophiles with Allyl–Metal Complexes

Palladium‐Catalyzed Electrophilic Allylation Reactions via Bis(allyl)palladium Complexes and Related Intermediates

“…[4,[15][16][17] Selective formation of this allylic isomer is in sharp contrast to the regioselectivity observed for palladium-catalyzed nucleophilic substitutions, which usually gives the linear allylic isomer. [2,20] The regioselectivity of the electrophilic attack can be explained by the influence of the substituent effects on the stability of the h 1 -allyl moiety of the bis(allyl)palladium intermediate. [15][16][17] DFT studies clearly show that the terminally substituted h 1 -allyl complexes are more stable when the alkyl or aryl substituents are attached at the C3 carbon atom of the allyl moiety (Scheme 10).…”

“…The allyl-palladium intermediate (20) of the catalytic transformation is generated by transmetallation of the allylstannane with the corresponding pincer complex. This intermediate was observed under the reaction conditions of the catalytic process.…”

“…On the other hand, palladium-catalyzed allylation reactions involving nucleophilic reagents (Scheme 1a) have been extensively reviewed, [1,3,[19][20][21][22][23] and, therefore, these reactions are not included in this paper.…”

Vinylepoxides in Organic Synthesis

“…With phthalimide as the pronucleophile and butadiene monoepoxide as the substrate, the Pd(0)-catalyzed transformation afforded the corresponding vinylglycinol derivative in high yield and with 98 % ee. 9.2.1.2 1,4-Additions 1,4-Additions of oxygen and nitrogen nucleophiles to vinyloxiranes can be achieved with Pd(0) catalysis [103,104]. Acetate, silanols, amines, sulfonamides, and azide have been used as nucleophiles, and the stereochemical outcome of these additions, where applicable, is normally the result of two consecutive S N 2 reactions.…”

“…9.2.3.1 S N 2' Additions 1,4-Additions of carbon nucleophiles to vinylepoxides are well documented and can be accomplished by several different techniques. Palladium-catalyzed allylic alkylation of these substrates with soft carbon nucleophiles (pK a 10-20) proceeds under neutral conditions and with excellent regioselectivities [103,104]. The sulfone 51, for example, was cyclized through the use of catalytic amounts of Pd(PPh 3 ) 4 and bis(diphenylphosphino)ethane (dppe) under high-dilution conditions to give macrocycle 52, an intermediate in a total synthesis of the antitumor agent roseophilin, in excellent yield (Scheme 9.26) [115,116].…”