A Short Synthesis of Cubane Key Words

Home , Cubane

J. C. BARBORAK, L. WATTS, R. PETTIT* (UNIVERSITY OF TEXAS, AUSTIN, USA) Category A Convenient Synthesis of the Cubane System Synthesis of Natural J. Am. Chem. Soc. 1966, 88, 1328–1329. Products and Potential Drugs A Short Synthesis of Cubane Key words

cubane O Br Diels–Alder reaction Ce4+ O Fe + O [2+2] cycloaddition OC CO 80% Br CO Br Favorskii Diels–Alder reaction O rearrangement AB C

ν h , PhH 80% [2+2] cycloaddition

1. SOCl2 2. t-BuO H 2 O O py, Et2O HO C 2 Br 3. Δ aq KOH, 100 °C CO2H Br 80% Favorskii rearrangement Cubane E D

Significance: In 1966, Barborak, Watts, and Pettit Comment: The authors’ route exploits the unique reported the total synthesis of cubane, a highly reactivity of cyclobutadiene–iron tricarbonyl A. symmetrical hydrocarbon. This synthesis appeared Upon oxidation, this complex acts as a cyclobuta- two years after Eaton’s and Cole’s seminal publica- diene precursor. Indeed, exposure to CeIV ions trig- tion, which was also highlighted in Synfacts (Syn- gers release of cyclobutadiene and reaction with facts 2019, 15, 613). Pettit’s insight into the chem- quinone B to give rise to Diels–Alder adduct C. Irra- istry of organometallic complexes and their diation of C enables a [2+2] photocycloaddition to application to the synthesis of complex targets yield polycyclic compound D. Two successive Favor- make this work another true classic in that area. skii rearrangements form the last two four-mem- bered rings. Decarboxylation via the tert-butyl per- ester leads to the target compound. This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

SYNFACTS Contributors: Erick M. Carreira, Felix Pultar Synfacts 04022020, 16(02), 0135 Published online: 21.01.20201861-19581861-194X