Stereoselectivity of Metal-Catalyzed Cyclizations of 1,6-Dienes

Abstract

In this article, the stereoselectivity of metal-catalyzed cyclizations of 1,6-dienes is examined according to the elementary steps which can be envisaged as triggers of the rearrangements. Crucial results have been obtained which demonstrate that enantioselective and diastereoselective cyclizations are possible. However, a lack of stereoselectivity is often observed for 1,6-dienes having a prochiral tether, which appears to originate in the lack of differentiation between the two olefins of the substrates.

Highly Diastereoselective Hydrosilane‐Assisted Rhodium‐Catalyzed Spiro‐Type Cycloisomerization of Succinimide and Pyrazolone‐Based Functional 1,6‐Dienes

“…Transition‐metal‐catalyzed cycloisomerization of α,ω‐dienes have been one of the most important and atom‐economic reaction processes in the construction of functionalized cyclic products that are fundamental constituents of pharmaceutical compounds and nature products, also in the field of functional materials [1] . In this regard, extensive studies have been carried out on the cycloisomerization‐type cyclization of α,ω‐dienes, promoted by various transition‐metal catalysts, including nickel, [2] palladium, [3] ruthenium, [4] titanium, [5] Lewis super acids, [6] and other metal catalysts [7] . Among these catalytic methods, the synthetic potential of rhodium in cycloisomerization of α,ω‐dienes has become an attractive strategy in the synthesis of carbocycles or heterocycles [8] .…”

Rhodium(III)-Catalyzed Asymmetric Borylative Cyclization of Cyclohexadienone-Containing 1,6-Dienes: An Experimental and DFT Study

“…The development of efficient asymmetric annulation protocols is particularly important in organic synthesis due to the wealth of carbo- and heterocycles in natural products, pharmaceutical compounds, and functional materials. In view of their importance, great efforts have been devoted to the development of transition-metal-catalyzed asymmetric cyclizations of 1,6-bifunctional molecules, typically involving 1,6-enynes and 1,6-dienes . In comparison to 1,6-enynes, the metal-catalyzed asymmetric cyclization of 1,6-dienes remains more challenging due to the requisite differentiation of the two olefins in 1,6-dienes.…”

Ir-Catalyzed cyclization of α,ω-dienes with an N-methyl group via two C–H activation steps

“…1 In this respect, catalytic cyclization reactions of non-conjugated 1, n -diynes 2 and -enynes 3 via C–H activation of the same or different molecules have been developed as useful transformations into diverse carbocyclic units. In contrast, the use of α,ω-dienes in the cyclization triggered by C–H activation has been underdeveloped 4 in spite of many reports on the transformations of α,ω-dienes by way of cycloisomerization, 5 silylation, 6 boration, 7 and the addition of organometallic reagents. 8 Chen and Hou reported scandium-catalyzed cyclization of 1,5- or 1,6-dienes with the aromatic C–H bond to give aryl-functionalized 1,3-disubstituted cyclopentane derivatives (Scheme 1a).…”