Science of Synthesis

de Meijere, A.; Kozhushkov, S. I., Science of Synthesis, (2009) 48, 504.

The cyclopropane-forming extrusion of one and two carbon monoxide molecules from cyclobutanones and cyclopentanediones, respectively (‌Scheme 29‌), as well as extrusions of carbon dioxide from γ-lactones to form cyclopropanes, can be induced by irradiation. The last reaction can also be brought about by heating with sodium chloride in dimethyl sulfoxide (Krapcho conditions[‌57‌]). These reactions are of some importance for the preparation of functionally substituted cyclopropanes (see Houben–Weyl, Vol. E 17b, p 995). However, until recently they had virtually no application for the synthesis of cyclopropane hydrocarbons ‌86‌, except for the very important first synthesis of the tetrahedrane ‌88‌, kinetically stabilized by sterically demanding substituents.[‌6‌,‌136‌] Thus, irradiation of the tetra-tert-butylcyclopentadienone isolated in an argon matrix with 254-nm light gives the tricyclopentanone ‌87‌ by intramolecular [2+2] criss-cross cycloaddition, as detected by IR spectroscopy. Continued irradiation leads to carbon monoxide extrusion, which completes the successful synthesis of tetra-tert-butyltetrahedrane (‌88‌).[‌137‌] Substantial quantities of di-tert-butylacetylene are also detected. The four bulky substituents in ‌88‌ prevent both its dissociation into two acetylene fragments as well as its thermal reorganization into tetra-tert-butylcyclobutadiene. The latter transformation has an activation barrier of 26 kcal·mol−1, while tetra-tert-butylcyclobutadiene can be converted back into tetrahedrane ‌88‌ photochemically. However, only tetrahedrane ‌88‌ can be synthesized by photochemical carbon monoxide extrusion from tricyclopentanone ‌87‌.[‌138‌] This strategy fails with other tetrasubstituted cyclopentadienones, even with bulky substituents (see below). Moreover, the yield drops to 13% when the tetra-tert-butylcyclopentadienone contains one perdeuterated tert-butyl group.

‌Meeeee 88‌ Meeeeeeee ee Meeee-eeee-eeeeeeeeeeeeeeeee ee Meeeeeeeeeeee Meeeee Meeeeeee Meeeeeeee eeee Meeee-eeee-eeeeeeeeeeeeeeeeeeeeee[‌888‌–‌888‌]

Meee eeee ee eeeeeeeeeeeeeee eee eeee ee eeeeeee eeeee eeeee eeeeeeeee eeee eeeeeee eeeeeee(M) eeeeeeeee. Meeeeee, eee eeeeee ee eee eeeeeeeeeeeee ‌88‌ eeeeeeeeeeeee eeeeeee eeee eee eeee ee eeeeeee(M) eeeeeeee ee eeee ee eee eeeeeeeeeeee ee eee eeeeeeeeeeeee eeeeeeee eeeeeeee (‌Meeeee 88‌).[‌888‌] Me eee eeeee eeee, eee eeee-eeeeeeee eeeeeeeeeeeeeee eeeeeeeeeeeeee ee eeeeeeeeeeeeee eeee eeeeeeeeeeeee eeeeeeeee ee eee eeeeeee(M)–eeeeeee eeeeeee ‌88‌ eeeee ee eee eeeeeeeeeeee eee eeee eeee ee eeeeeeeeeeee eeeeeeeee, eeeeeee ee eee ee eeeeeeee ee e eeeeeee eeee ee eeeeeeeee eeeeeeeeeeee (eeeeeeeeeeeee, e eeeeeeee eeeeeeeee eeeeeeee ee eee eeeeeeeee).[‌888‌]

‌Meeeee 88‌ Meeeeee(M)-Meeeeeeee Meeeeeeee ee Meeeee Meeeeeee eeee Meeeeeeeeeeeee[‌888‌,‌888‌]

Meeeeee eeeeeee ee eeeee eeeeeeeee ee eee eeeeeeeee-eeeeeeeee eee-eeeeeeeeeeeeeeeeeeeeeeee ee eeeeeeeeee eee eeeeeeeeeeeee eeee eeeeeeeeeeeeee, eeeee eeee eeeeee eeeeeeee eee eeeeeee [8+8] eeeeeeeeeeeee ee eeeeeeeeeeeeee eeee e eeeeee eeee, eeeeeeee ee eeeeee eeeeeeee eeeeeeeee eeee eee eeeeeeeeeeee eeeeeeeeeeeee eeeee eeeeeeeee eeeeeeeee ee eeee eee eeeeeeeeeeee eeeeeeee ‌88‌.[‌888‌]

Meeee eeeeeee eeeeeeeeee, eee eeee eeeeeeeee(MM) eeeeeeee ee e eeeeeeee, eee eeeeeeee eeeeeeeeeeeeeeeeeeeee eeeeeee eeeeeeeeeeee-ee-eeeeeee eeee-eeeeeee eeeeeeeee eeeeeee ee eeeee eeeee ee ‌Meeeee 888‌ (eee Meeeeee ‌88.8.8‌).[‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeee-eeee-eeeeeeeeeeeeeeeee (‌88‌):[‌888‌]

M eeee ee eeeee-eeee-eeeeeeeeeeeeeeeeeeeeee (8.88 e, 8.88 eeee) ee e eeeeeee ee 8,8-eeeeeeeeeeeeee/eeeeeee (8:8; 888 eM; eeeeee eeeeeee) eee eeeeeeeeee ee −888°M eee 888 e eeee eeeee eeee e eeeeee eeee (λ = 888 ee, 888 M) ee e eeeeeeeeeeeee eeeeeee (eeeeee 888 eM). Mee eeeeeee eee eeeeeee ee e eeeeee Meeee eeeeee eeeeee eeee eee M8 eee eeeeeeee eeee ee eeeeeeeee eeeeeee eeeeee. Meee eeeee ee eeeeeeeeeee eeeeeeee ee. 888 M ee eee M8. Mee eeeeeee eee eeee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Meeeee eeeeeeeeeeeeee ee eee eeeeeee ee −88°M (eeeeee eee, eeeeeee/Me8M 88:8), eeeeeeee ee eeeeeeeeeee ee 88°M/8 Meee, eeeeeeeee eeeeeeeee eeeeeeee ee eee eeeeeee; eeeee: 888 ee [88% (ee. 88% eeeeee eeee eeeeeee eeeeeeeee eeeee-eeee-eeeeeeeeeeeeeeeeeeeeee)]; ee 888°M; MM (Meeee) ν̃eee: 8888, 8888, 8888, 8888, 8888, 8888, 8888, 888, 888, 888, 888, 888 ee−8; 8M MMM (MMMe8, δ): 8.88 (e, 88M); 88M MMM (MMMe8, δ): 88.8 (M), 88.8 (M), 88.88 (MM8).

8,8-Meeeeeeeeeeeeeeeeeee (‌88‌, M8 = M8 = Me); Meeeeee Meeeeeeee:[‌888‌]

M eeee ee [Me(eee)(eeee)]MM8 (8.8 ee, 8 μeee) eee 8,8-eeeeeeeeeeeeeeeeeeeee (88.8 ee, 8.88 eeee) ee eeeeeee (8 eM) eee eeeeee ee eeeeee eee 88 e eeeee ee eeeee eeeeeeeeee. Mee eeeeee eeeeeee eee eeeeeeee eeeeeee e eee ee Meeeeeee eee eee eeeeeeee eee eeeeeeee ee eeeeeeeeeee MMM (eeeeee eee, eeeeee) ee eeeeee e eeeeeeeee eee; eeeee: 88.8 ee (88%); 8M MMM (MMMe8, δ): 8.88 (e, 8M, eeeeeeeeeee-M), 8.88 (e, 8M, MM8), 8.88–8.88 (e, 88M, eeee-M); 88M MMM (MMMe8, δ): 88.8 (8MM8), 88.8 (M), 88.8 (8MM8), 888.8 (8MM), 888.8 (8MM), 888.8 (8MM), 888.8 (M).

eee-8,8-Meeeeeeeeeeeeeee[8.8.8.88,8]eeeeee [‌88‌, M = (MM8)8] eee eee-8,8-Meeeeeeeeeeeeeee[8.8.8.88,8]eee-8-eee (‌88‌, M = MM=MM); Meeeeee Meeeeeeee:[‌888‌]

M eeeee-eeeee Meeeeee eeee eee eeeeeee eeee eeeeeeeeeeeeee (8.8 eeee), eeeeeeee ee Me eeeeeeee (8.8 eeee), MeMM (8.8 eeeee), eeeeee (88 eeee), eee eeeee MM8Me8 (8 eM) ee e eeeeeeee. Mee eeee eee eeeeee eee eeeeeee ee eeeee ee e eeeeeeeeeee-eeeeeeeeee eee eeee ee 888°M. Meeee 88 e, eee eeeee eeeeeeee eee eeeeee ee ee eee eeeeeeee eeeeeee e eee ee eeeeee eee, eeeeeee eeee MM8Me8. Meeeeeeeeeee eee eeeeeeee eeeee eeeee eeeeeeeeeeeeee.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 88/8, 88.
• 8.Meeeee-Meee, (8888) M 8e, 88.