Synthesis of Functionalized Medium‐Sized trans‐Cycloalkenes by 4π Electrocyclic Ring Opening/Alkylation Sequence

Abstract

Development of an ovel synthetic method for medium-sized trans-cycloalkenes (TCAs) is described. Functionalized TCAs are readily prepared from simple cycloalkanones in af ew steps,n amely,e nol silyl ether formation, [2+ +2] cycloaddition, and domino 4p electrocyclic ring opening/alkylation (conjugate addition). The first example of central-to-planar chirality transfer from enantiomerically enriched cyclobutenes to TCAs is also described.

Designing Donor‐Acceptor Cyclopropane for the ThermalSynthesis of Carbocyclic Eight‐Membered Rings

“…At 160 °C, the major product formed is A1 (75 : 25), whereas at 120 °C A2 is observed predominantly (40 : 60). Trans ‐cyclooctenes are known to display atropisomerism, [23d] however little is known on atropisomerism of ( E,Z )‐cycloocta‐1,4‐diene [24] …”

Synthesis of γ-Aryl Medium-Sized Cyclic Enones by a Domino 4π-Electrocyclic Reaction/Heck–Matsuda Arylation Sequence at Ambient Temperature

“…We have reported chirality-transfer reactions of optically active cyclobutenes 1 through the short-lived planar chiral intermediates 2 . 7a b It would be expected that the point chirality of 1 would be transmitted to the γ-position in 5 if the reaction does not proceed via 3 as an achiral intermediate; therefore, we used optically active 1a as the starting material. To our delight, the chirality of (–)- 1a (>99% ee) was perfectly transferred to (–)- 5aa (>99% ee), which rules out the formation of diene 3aa (Scheme 5 ).…”