Cobalt-catalyzed branched selective hydroallylation of terminal alkynes

Abstract

Here, we reported a cobalt-hydride-catalyzed Markovnikov-type hydroallylation of terminal alkynes with allylic electrophile to access valuable and branched skipped dienes (1,4-dienes) with good regioselectivity. This operationally simple protocol exhibits excellent functional group tolerance and exceptional substrate scope. The reactions could be carried out in gram-scale with TON (turn over number) up to 1160, and the products could be easily derivatized. The preliminary mechanism of electrophilic allylation of α-selective cobalt alkenyl intermediate was proposed based on deuterium labeling experiment and kinetic studies.

Cobalt‐Catalyzed Hydroalkylation of Alkenes and Alkynes: Advantages and Opportunities

“…Shortly after, Lu's group reported branched selective hydroallylation and hydroalkylation of terminal alkynes using NNN ‐cobalt pincer complex as catalyst (Scheme 6). [12] Both allyl bromide and benzyl bromide were competent in this reaction. Control experiments were conducted to explore the reaction mechanism.…”

Metal-catalyzed Markovnikov-type selective hydrofunctionalization of terminal alkynes

“…In 2022, Lu and co-workers used cobalt–hydride catalyst to achieve branched selective hydroallylation of terminal alkynes to synthesize the branched skipped 1,4-dienes (Scheme 24(b)). 104 The reactions could be carried out in gram-scale, and the turn over number (TON) was up to 1160.…”

Divergent 1,2-carboallylation of terminal alkynes enabled by metallaphotoredox catalysis with switchable triplet energy transfer

“…1 Therefore, the development of efficient methods for constructing these skipped dienes has received increasing attention. Among various synthetic methods developed, 2–5 transition metal-catalyzed hydroallylation of alkynes represents one of the most straightforward and reliable approaches to accessing skipped dienes. 5 Since the seminal report by Trost in 1998, 5 a a number of elegant examples of catalytic hydroallylation of alkynes, enabled by stoichiometric reductants or hydrides in the presence of nickel, copper, or cobalt catalysts, have later been developed by several other groups, providing efficient and regioselective methods for the synthesis of skipped alkenes.…”

“… 5 Since the seminal report by Trost in 1998, 5 a a number of elegant examples of catalytic hydroallylation of alkynes, enabled by stoichiometric reductants or hydrides in the presence of nickel, copper, or cobalt catalysts, have later been developed by several other groups, providing efficient and regioselective methods for the synthesis of skipped alkenes. 5 Despite these advancements, selective assembly of highly substituted 1,4-dienes remains challenging.…”