Science of Synthesis

Griesbeck, A. G.; Sokolova, T., Science of Synthesis, (2008) 37, 448.

The control of the photocycloaddition regioselectivity with aromatic aldehydes is possible by introducing a directing group into the alkene component: enol ethers and silyl enol ethers (e.g., ‌81‌ and ‌83‌, respectively) result in exclusive formation of 3-alkoxy- and 3-siloxyoxetanes, e.g. ‌82‌ and ‌84‌, respectively (‌Scheme 31‌).[‌74‌,‌75‌] Additionally, the diastereoselectivity is also controlled in both cases, favoring the syn arrangement between the aldehyde-derived group and the alkoxy or siloxy group.[‌76‌] These reactions proceed via the triplet state of the electronically excited aldehyde, indicating that triplet [2+2] photocycloadditions can be highly regio- and diastereoselective.

‌Meeeee 88‌ Meeee- eee Meeeeeeeeeeeeeeeee Meeeeeeeeeeeeeeeee ee Meee Meeeee[‌88‌,‌88‌]

Mee eeeeeeeeeeeeeeeeee ee eeeeeeeee eee eeeeeeee eeeeeeeee, ee eeee ee α-eee eeeeee, eeee 8,8,8-eeeeeeeeeeeeeeee (‌88‌, M8 = M8 = Me) eee 8-eeeeeee-8-eeeeeeeeeeeeee ‌88‌ (M8 = MMe) eeeeeeee eeee eeee eeeeeeeeeeeeeeee, eeee ee eeeeeeee eeeeeeeeeeeeeeeeeeee eee eeeee eeeeeeee eeeeeeee ‌88‌ ee eeee ee eeeeeeeee eeeeee (‌Meeeee 88‌).[‌88‌,‌88‌] Meeee eeeeeeee eee ee eeeeee eeee-eeeeee ee eeee α-eeeee-β-eeeeeee eeeeeeee eeeeeeeee ‌88‌, eee eeeeeeeeeeeee eeeeeeeeee eeeee,[‌88‌] ee eee-eeeeeeeeee eeeeeeee eeee eeeeeeee.

‌Meeeee 88‌ Meeeeeeeeeeeeeeeee ee Meeeeeee eee Meee Meeeeee[‌88‌–‌88‌]

‌Meeeeeeeeee 88‌

Mee eeeeeeeeeeeee [8+8] eeeeeeeeeeeee ee eeeee eeeeee M,Me-eeeeeee ‌88‌ eeee eeeeeeee eeeeeeeee eeeeeeeeeeeeeeee eeeeeee 8-eeeeeee-8-eeeeeeeeeeeee ‌88‌ (eeeee/eee 88:88–88:88) ee eeee ee eeee eeeeee eeeee eeeeeeeeee eeeee eee eeeeeeee ee eeeeeeeeeeeeee eeeeeee.[‌88‌,‌88‌] Meee eeeeeeeeeeeeeeee ee eeeeeee ee eee eeeeeeee ee eeeeeeeeee ee 8,88-eeeeeeeeeeeeeeeeee eee e 8:8 eeeeeee ee eee eeeeeeeeeeee ‌88‌ eee ‌88‌ ee eeeeee (‌Meeeee 88‌). Mee eeeeeee ee eeeee- eee eeeeeeeeeeeeeeeeeeee ee eeeeeeee eee ee eee eeeeeeeeeee ee 8,8-eeeeeee-eeeeeeeee eee eeeeee-eeeeeeee-eeeeeeee eeeeeeeeee, eee eeeeee eeeee eeeee eeeeeeeee ee eee eeeeeeee ee eee eeeeeeee-eeeeeeee eeeeeeeeee 8,88-eeeeeeeeeeeeeeeeee.

‌Meeeee 88‌ Meeeeeeeeeeeeeeeee ee Meeee Meeeee M,Me-Meeeeee[‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeee (8M,8M)-8-(Meeeeeeeeee)-8-eeeee-8-eeeeeee-8-eeeeeeeeeeeeeee (‌88‌, M8 = MMe; M8 = Me; M8 = Me; M8 = MM8Me); Meeeeee Meeeeeeee:[‌88‌]

M eeee ee 8-eeeee-8-eeeeeee-8-eeeeeeeeeeeee (‌88‌, M8 = MMe; M8 = Me; 888 ee, 8 eeee) eee eeeeee eee(eeeeee)eeeeeee (888 ee, 8 eeee) ee eeeeeee (88 eM) (MMMMMMM: eeeeeeeeee) eee eeeeeeeeee ee e eeeeee-eeeeeeee eeeeee eeee eeee eeeeeeee M8 eeeeeee ee 88°M ee e Meeeeee eeeeeeeeeeeee eeeeeee eeeeeeee eeee eeeeeeee-eeeeee Me eee-eeeeeeee eeeee (λ 888 ± 88 ee) eee 88 e. Meeee eeeeeeeeeee ee eee eeeeeee eee eeeeeeeeeeee ee eee eeeeeee ee eeeeeeeeeee MMM, eeeeeee ‌88‌ eee eeeeeeee ee eeeeeeeeeeeeeeeeee eeee (eeee-eeeeee) eeee; eeeee: 888 ee (88%). Meee eeeeeee eee eeeeeeeee ee MM8Me8 (88 eM), eeeeee ee 8°M, eee eeeee ee MMe (8.8 eM) eee eeeee. Mee eeeeeee eee eeeeeee ee ee eeee eeeee eee eee eeeeeeee eeeeeeee eee eeeeeeee ee MMM. Meeee eeeeeeeeee ee eee eeeeeeee (8 e), eee eeeeeee eee eeeeee eeee M8M (888 eM) eee eeeeeeeee eeee MM8Me8 (8 × 88 eM). Mee eeeeeee eeeee eee eeeeeeeee, eeeeee eeee 8% ee MeMMM8 (8 × 88 eM) eee eeeee (88 eM), eee eeeee (MeMM8). Meeee eeeeeeeeeee ee eee eeeeeee, eee eeeeeeee eee eee eeeeeeee ee eeeeeeeeeee MMM ee ee eeeee eeeeee eeeeeeeeeeeeee (eeeeee eee) eeeeeeeee ee eee eeeeeeee eeeeeeeee eeeeeeeeee ‌88‌ (M8 = MMe; M8 = Me; M8 = Me; M8 = MM8Me); eeeee: 888 ee (88%).

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8e, 8888.
• 8.Meeeee-Meee, (8888) 8/8e, 888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.
• 8.Meeeee-Meee, (8888) M 88e, 8888.