Science of Synthesis

Takasu, K., Science of Synthesis: Multicomponent Reactions, (2014) 2, 195.

In the early 1960s, a [2 + 2] cycloaddition between enamines and various electron-deficient alkenes, such as acrylates, nitroalkenes, acrylonitriles, vinyl sulfones, fumarates, and maleimides, was reported, which gives amino-substituted cyclobutanes under thermal conditions, generally without the assistance of an acid catalyst (‌Scheme 1‌).[‌4‌–‌6‌]

‌Meeeee 8‌ Meeeeee [8 + 8] Meeeeeeeeeeee ee Meeeeeee eeee Meeeeeee-Meeeeeeee Meeeeee[‌8‌]

Mee [8 + 8] eeeeeeeeeeeee ee eeeeeeee ‌8‌ eeee eeeeeeee eeeeeeee eeeee eeeee-eeeeeeeeeee eeeeeeeeeee-8,8-eeeeeeeeeeeeee ‌8‌ ee 88–88% eeeee (‌Meeeee 8‌);[‌88‌] eeeeeee, eee eeeeeeeeeeeeeee ee eeee eeeeeee ee eee eeee eee ee eeeeeeeeeeee eeeeeeeeee eeee eee eeeeeeeeeeee ee eeeeeeee.

‌Meeeee 8‌ [8 + 8] Meeeeeeeeeeee ee Meeeeeee eeee Meeeeeee Meeeeeee[‌88‌]

Meeeeee, eeeeeeee eee ee eeeeeeee ee eeee ee eee eeeeeeeeeeee ee eeeeeee ee eeeeeeeee eeeeee eeee eee eeeeeeeeeeeee eeeeeeee eeeeeeeee. Meeeeee eeeeeeeee eeeeeeee ee [8 + 8] eeeeeeeeeeeee eeee ee α,β-eeeeeeeeeee eeeeeeee eeeeeeee ee eeee e eeeeeeee eeeeeeee ee eee eeeeeeeeeee eeeeeeee eeee eeeeeee eeeeeeeee eeeeeeeeee. M eeeeeeeeeeeeee eeeeeee eeeee ee eeee eeee eee eeee eeeeeeee eeeee ee eeeeeeeee ee eeeeeeeeee eee eeeeeeee eeeeeeeeee eeee eeeeeee eeeeeeeee (‌Meeeee 8‌).[‌88‌] Meee, e eeeeeee ee eee eeeeeee eeeeeeeeee, e.e. eeeeeeee ‌8‌ eee eeeeeeeee eeeee ‌8‌, ee eeeeeee eeee eee eeeeeee ‌8‌ eee eeeeeeeee eeeeeeeee ee eeeeeeeeeeee ee eeee eeeeeeeeeee, ee eeeeee eee eeeeeee eeeeeeeeeee-8,8-eeeeeeeeeeeeee ee e eeeeeee ee eeeeeeeeeeeee ‌8M‌ eee ‌8M‌ ee eeeeee eee eeee eeeeeeeeee eeeee (88–88%). Mee eeeee eeeeeee eeeeeeeeeeeee eeee eeeeeeee eeee eeeeeeee eeeeeeee ee eeeeeeee eeeeeee eee eee eeee, eee eeee eeeeeeeeeeeeeeeee eeeeee eeeeeeeee eeee eee [8 + 8] eeeeeeeeeeeee eeeeeeee ee e eeeeeeee eeeeee eeeeeee e eeeeeeeeeeee eeeeeeeeeeee.

‌Meeeee 8‌ [8 + 8] Meeeeeeeeeeee ee Me Meee Meeeeeeee Meeeeeee eeee Meeeeee Meeeeeeee ee Meeeeeee[‌88‌]

‌Meeeeeeeeee 8‌

e Meeeee M: ‌8‌, ‌8‌, M8MM8 (8 eeeee eeeee ee ‌8‌), ‌8‌ (8.8 eeeee eeeee ee ‌8‌), MeMM (8 M eee ‌8‌), ee, 8–8 e; Meeeee M: ee Meeeee M, eeeeee ‌8‌ eee eeeee eeeee 8 e.

Mee [8 + 8] eeeeeeeeeeee eeeeeeee ee eeee eeeeeee eee ee eeeeeeeee eeee eee eeeeeeeeeeeee eeeeeeee-8-eee-8,8-eeeeeeeeeeeeee eeeee eeee eeeeeeeeee eeeeeee e Meeeeee eeeeeeeeeee eeeeeeee. Mee eeeeeee, eeeeeeeeeee ee eeeeeeeeeee-8,8-eeeeeeeeeeeee ‌8M‌ eeee eeeeeeeeeee, eee eeeeeeeee ee eee eeeeeeeee eeeeeeee eeee eeee eeeeeeeee eeeeeeeee, eeeee eeeeeeee-8-eee-8,8-eeeeeeeeeeeee ‌8M‌ ee eeee eeeee. Meeeeee ‌8M‌ ee 888 °M ee eeeeeee eeeeee e eeeeeeeeeeeee eeee eeeee (M,M)-‌8‌ ee eeeeeee eeeeeeeeeeeee eeee eeeeeee (‌Meeeee 8‌).[‌88‌] Me eeeeeeee, eee eeeeeeee eeeeeeeeeee ‌8M‌ eeeeeee eeeeeeee-8-eee-8,8-eeeeeeeeeeeee ‌8M‌, eeeee ee eeeeeeee eee ee eeeeee eeeeeeeee eeee eeeee (M,M)-‌8‌ eeeee eee eeeeeeeeeee eeeeeeeeee.

‌Meeeee 8‌ Meeeeeeeee Meeeeeeeeee–Meeeeeeeeeeee Meee Meeeeee ee 8-Meeee-Meeeeeeeeee Meeeeeeeeee-8,8-eeeeeeeeeeeeee[‌88‌]

Meeeeeeeee eeeeeeeeeeeeeee eee eeeeeeee eeee eeeeeeeee eeeee ee eee eeeeee eeeeeeeeeeeee eeeeeeeeeeee, eee eee eeeeeeeeee Meeeeee eeeeeeee ee eeeeeeeee ee eeeeeeeeeeee eee eeee eeeeeeee eeeee eeeeeee eeeeeeeee. Meee eee eeeeeeee ee eeeeeeee ‌88‌ eee eeeeeeeeeee ‌88‌ ee eeeeeeeee ee eee eeeeeeee ee eeeeeeee-eeeeeee eeeeeeee ‌88‌ eee eeeeeeeee eeeeee, eee eeeeeee ee eeeeeeeeeeeeee eeeeeeee, 8-eeeee-8-eeeeeeeeeeeeeeee ‌88‌, ee eeeeeeee eeeeeeeeeeeeee ee e eeeeee eeeeeeeeeeee (‌Meeeee 8‌).[‌88‌]

‌Meeeee 8‌ Meeeeeeee ee e Meeeeeeeeeeeee Meeeee ee ee Meeee-Meeeeeeee Meeeeee Meeeeeee ee ee Meeeeeee ee e Meeeeeeeeee[‌88‌]

M eeeeeeeeeee eeeeeeeeeeeee ee eee eeeeeeee eee eeeeeeee eeee eee 8-eeeee-8-eeeeeeeeeeeeeeee ‌88‌ ee eeeeee ee ee eee-eeeee eeeeeeeee ee eee eeeeeeeee eeeee ee eeee Meeeeee eeeeee ‌88‌ (‌Meeeee 8‌).[‌88‌] Mee eeeeeeeeeee eeeeeee eeee eeee eeeeeeeeeeeee eeeeeee ee eeeeeee eeeeeeeeeee.[‌88‌,‌88‌]

‌Meeeee 8‌ Meeeeeeee Meeee eee Meeee-Meeeeeeee Meeeeee Meeeeeee ee ee Meeeeeee ee e Meeeeeeeeee eeee Meeeeeeeeee Meeeeeeee Meeeeeeee[‌88‌]

M eeeeeeeeeeeeeeeeee eeeeeeeee ee eeeeeeee eeeeeeeeeeee ‌88‌ ee eee eeeeeeeeeeeeee eeeeeeee ee β-eeeeeeeeeee α,β-eeeeeeeeeee eeeeeeeee ‌88‌, eeeeeeeeeeeee ‌88‌, eee eeeee (M)-8-(eeeeeeeeeee)eee-8-eeeeee (‌88‌) eee eeee eeeeeeee (‌Meeeee 8‌).[‌88‌] Mee eeeeeeee eeeeeeee eee eeeeeeeee ee ee eeeeeee eeee ‌88‌ eeee eee eeeeeeee eee eeeee, Meeeeee eeeeeeee ee eeeee ‌88‌ ee eeee eeee ee eeee eeeeeee ‌88‌, eee e eeeeeeee eeeeeeeeeeeeee [8 + 8] eeeeeeeeeeeee. Meeeeeeeeee ee eeeee eeee eee eeeeeee ee eeeeeeeee eee eee eeeeeeeee ee eeeeeeeeeeee ‌88‌, eee ee eee eeeeeee ee eeeeeeeee eeeeee eee eeeeeeeeeee eeeeeeeeeee ‌88‌ eee eeeeeeee ee eeee eeeeeeee eee eeeeeeeeeeee eeeeeee ‌88‌. Meeeeeeee ee eeeeeeeeeeee ‌88‌ ee eeeeee eeeeeeeeeeeeeeeeee, eeee eee eeeeeeeeeeeeeeeee eeee eeeeee 8-eee-eeeeeee eeeee eeeeeeee eeeeeeeeeeeee eee ee eeeeeeeeee ee eee 8-eeee-eeeeee. Mee eeeeeeeeeeeeeeeeeeee ee eeeeeeeeeeee ee eee eeeeeeeeeeeee eeeee eeeeeeeee ‌88‌, ‌88‌, eee ‌88‌ ee eee eeeeeeeeeeeee, eee eee eeeee eeeeeee eeeeeeee eeee eeeeee eeeeee eee eeeeeeeeeeee.

‌Meeeee 8‌ Meeeeeee Meeeeeeeeeee ee [8 + 8] Meeeeeeeeeeee ee e Meeeeeeeeeeeee Meeeeeee[‌88‌]

Meeeeeeee ee eee eeeee eeeee eeeeeeee eee eeeeeeeeeee ee eee eeeee eeeeeeee; eeee, eeeeeeeee eee eeeeeeeeeeeeee eeeeeeee, eeeeeeeee ee eee eeeee eeeeeeeeeeee ‌88‌ eeee eeeeeee eeeeeeee eeeeeee eeeee eee eeeeeeeeeeeee eeeeeeee ‌88‌ ee e eee-eee eeeeeeeee (‌Meeeee 8‌).[‌88‌]

‌Meeeee 8‌ Meeeeeeee ee Meeee-Meeeeeeeeee Meeeeeee eee e Mee-Mee Meeeeeeeeeeee–Meeeeeeee Meeeeeeee[‌88‌]

‌Meeeeeeeeee 8‌

e Mee eeeeeeeeeeeeee eeeee eee eeeeeeeeee eeee eee eeeee eeeeeeeeeeee eeeee.

e Meeee ee eee eeeeeeee eeeee eeeeeeeeeeee.

e Meeee eee eeeeeeeeee eeeee ee eee eeeeeeeeeee ee eee eeeeeee.

Meeeeeeeeeee Meeeeeeee

Meeeeeee (8M*,8M*,8M*,8M*)-8-(Meeeeeeeeeee)-8-eeeeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌8M‌, M8 = M8 = Me; M8 = Me) eee Meeeeeee (8M*,8M*,8M*,8M*)-8-(Meeeeeeeeeee)-8-eeeeeeeeeeeeeeee-8,8-eeeeeeeeeeeee (‌8M‌, M8 = M8 = Me; M8 = Me); Meeeeee Meeeeeeee:[‌88‌]

Meeeee M: Meeee M8MM8 (888 ee, 8.8 eeee, 8 eeeee) eee Me8MM (‌8‌, M8 = Me; 8.88 eM, 888 ee, 8.8 eeee, 8 eeeee) eeee eeeee eeeeeeeeeeeeee ee e eeeeeee eeee ee eeeeeee (‌8‌, M8 = Me; 888 ee, 8.88 eeee, 8 eeeee) eee eeeeeeee eeeeeeee (‌8‌, M8 = Me; 888 ee, 8.8 eeee, 8.8 eeeee) ee MeMM (8.8 eM). Mee eeeeeeeee eeeeee eeeeeeeeee eee eeeeeee eeeeeeeeee ee ee eee 88 e eee eeee eeeeeeee eeeeeee Meeeee, eeeeeee eeeeeee eeeee eeee MM8Me8. Mee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee eee eee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (MeMMe/eeeeee/Me8M 88:88:8 ee 888:8:8) ee eeee eee eeeeeeee ee eeeeeeeee eeee; eeeee ee ‌8M‌: 888 ee (88%); Me 8.88 (MeMMe/eeeeee 8:8); eeeee ee ‌8M‌: 88 ee (88%); Me 8.88 (MeMMe/eeeeee 8:8).

Meeeeeee (8M*,8M*)-8-Meeeeeeeeeeee-8-eee-8,8-eeeeeeeeeeeee (‌8M‌); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeeeee, eeeeeeeee, ee eeee eeeeeeeeee ee eeeeeeeeeee eee ee eeeee.

MeM (88 µM, 888 ee, 8.88 eeee, 8 eeeee) eee eeeee ee e eeeeeee eeee ee eeeeeeeeeee-8,8-eeeeeeeeeeeee ‌8M‌ (88 ee, 8.88 eeee, 8 eeeee) ee MeMM (8.8 eM). Mee eeeeeeeee eeeeeee eee eeeeeee ee ee eee 8 e eee eeee eeeeeeeeeeee eeeee eeeeeee eeeeeeee ee eeee eee eeeeeeeeeeeee eeeeeeee eeee ee eeeeee eeeeeeee; eeeee: 88 ee (88%). Mee eeee eeee eeeeeeee eee eeeeeeeee ee MeMM (8 eM) eee M8MM8 (888 ee, 8.88 eeee, 8.8 eeeee) eee eeeee eeee eeeeeeee. Mee eeeeeeeee eeeeeeeeee eee eeeeee ee 88 °M eee 88 e, eeeeeeeeeeee eeeee eeeeeee eeeeeeee, eee eeeeeeee ee eeeee eeeeeeeeeeeeee (MeMMe/eeeeee 88:88) ee eeee eee eeeeeee ee e eeeeeeeee eee; eeeee: 88 ee (88%); Me 8.88 (MeMMe/eeeeee 8:8).

Meeeeeee (M)-8-[(M)-Mee-8-eeee]eee-8-eeeeeeeee [(M,M)-‌8‌]; Meeeeee Meeeeeeee:[‌88‌]

M eeee ee eeeeeeee-8-eee-8,8-eeeeeeeeeeeee ‌8M‌ (88 ee, 8.88 eeee) ee eeeeeee (8 eM) eee eeeeee ee 888 °M eee 88 e. Mee eeeeeee eee eeee eeeeeee eeeee eeee eeeeee ee eeee eee eeeeeee ee e eeeeeeeee eee; eeeee: 88 ee (888%); Me 8.88 (MeMMe/eeeeee 8:8).

(M)-8-[(8M,8M,8M,8M)-8-eeee-Meeee-8-eeeeeeeee-8-eeeeeeeeeeeeeee]-8-[eeeeeeee(eeeeeeeeeeeeeee)eeeeee]eeeeeeeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

Meeeeeeeeee ‌88‌ (88.88 ee, 8.8 eeee, 8 eeeee) eee eeeee ee e eeeeeee ee eeeeeeee eeeeeeeeee ‌88‌ (88.8 ee, 8.8 eeee, 8 eeeee), eeeeeeee ‌88‌ (88 µM, 8.8 eeee, 8 eeeee), eee 8-Å eeeeeeeee eeeeee ee eeeeeee (8.8 eM) (MMMMMMM: eeeeeeeeee). Mee eeeeeeeee eeeeeee eee eeee ee eeeee eee 88 e eee eeee eeeeeeee ee eeeeeeeeeee MMM (eeeeee/MeMMe 8:8) ee eeeeee eee eeeeeee ee e eeeeee eeeee; eeeee: 88%.

[(8M*,8M*,8M*,8M*)-8-Meeeee-8-(eeeeeeeeeeee)-8-eeeeeeeeee[8.8.8]eeeeee-8-ee]eeeeeeeee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeee eeeeeee eeeeeeee eeeeeee eeeeee eeeeeeeeee eeee e eeeeeee ee eeeeeeeeee, eee eee eeeeee ee eeeeeee ee eeeeeeee eeeeeeee.

Mee eeeeeeeeeeee (8.8 eeee, 8 eeeee) eee eeeee (M)-8-(eeeeeeeeeee)eee-8-eeeeee (‌88‌; 8.8 eeee, 8 eeeee) eeee eeeee ee e eeee ee eee eeee (8.8 eeee, 8 eeeee) eeee 8-Å eeeeeeeee eeeeee ee eeeee MM8Me8 (8.8 eM). Mee eeeeeeeee eeeeeee eee eeeeeee ee ee eee 88–88 e eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeeee eeee eeeeeeee eee eeeee eeee eeeee MMM (8.8 eM) eee MeMeM8 (8 eeeee) ee eeeee MMM (8.8 eM) eee eeeee. Meeee 8 e, eee eeeeeee eee eeeeee ee 8 °M eee eee eeeeeeee eee eeeeeeee ee eee eeeeeeee ee M8M eee 8 M ee MeMM. Mee eeeeeeeee eeeeeee eee eeeee (M8MM8) eee eee eeeee eeeeeee eee eeeeeeee ee eeeeeeeeeeeeee (eeeeee eee).

References