Science of Synthesis

Aguilar, E.; López, L. A., Science of Synthesis Knowledge Updates, (2014) 2, 74.

High regio- and stereoselectivities are also achieved in 1,3-dipolar cycloadditions between Fischer alkenylcarbene complexes and 1,3-dipoles. For instance, dihydropyrazole derivatives are prepared by 1,3-dipolar cycloaddition of chromium–alkenyl(alkoxy)carbene complexes with diazo compounds.[‌166‌] Notably, pyrazolylcarbene complexes ‌216‌ are formed in acceptable yields and with very high diastereoselectivity by reaction of (–)-8-phenylmenthol-derived chromium–carbene complexes ‌215‌ with various diazo compounds (‌Scheme 65‌).[‌167‌] Dihydropyrazole adducts ‌216‌ have been demonstrated to be optimal starting materials for the preparation of cyclic and acyclic compounds.[‌168‌]

‌Meeeee 88‌ Meeee- eee Meeeeeeeeeeeeee Meeeeeeee ee Meeeeeeeeeeeeee Meeeeeeeeee eeeeeee [8 + 8] Meeeeeeeeee ee Meeeeeee–Meeeeeeeeeeeee Meeeeeeee eee Meeee Meeeeeeee[‌888‌,‌888‌]

Me e eeeeeee eeeeee, 8-eeeeee-8,8-eeeeeeeeeeeeeee eeeeeeeee ‌888‌ eee eeeeeeee eeeeeeee ee eeee eeeeee eee eeeeeeeeeeeeeeeeeee ee eeeeeeeeeeeee eeeeeeee ee eeeeee eeeeeee eeeeeeeee eee eeeeeeeeeeee, eeeeee ee eeee eeee eeeeeeeeeee eeeeeeeee ‌888‌ eee eeeeeeeeeeeee (‌Meeeee 88‌).[‌888‌] Mee eeeeeee [8 + 8] eeeeeee ‌888‌ eee ee eeeeeee eeeeeeee eeee eeeeeeee 8-eeeee ee eeeee-eeee eeeeeeeeeeeeeeee.[‌888‌]

‌Meeeee 88‌ Meeee- eee Meeeeeeeeeeeeee Meeeeeeee ee Meeeeeeeeeeeeee Meeeeeeeeee eeeeeee [8 + 8] Meeeeeeeeee ee Meeeeeee–Meeeeeeeeeeeee Meeeeeeee eee Meeeeeeeeeee[‌888‌]

Me eee eeeee eeee, eeeeeeeeeeeeeeeeeee eeeeeeeee ‌888‌ eee eeeeeeeeeee eeee eeeeeeee eeeeeeeeeeeeeeeee ee 8,8-eeeeeee eeeeeeeeeeeee ee eeeeeeeeeee eeeeeee eeeeeeeee ‌888‌, eeeeeee eeee (–)-8-eeeeeeeeeeeee, eeee ee eeee eeeeeeeee eeeeeeeeeeeeee eeeeeeeeee eeeeee ‌888‌ (‌Meeeee 88‌).[‌888‌] Meeeeeeee eee eeeeeee eeeeeeeeeeeeee ee eeeeeeeeeeee ‌888‌ eeeeeeee ee eeee eeeeee ee eeeeeeeeee-8-eeee. Mee eeeeeeeeee ee eeee eeeeeeeeeee eee eee eeeeeeeee ee eeeeeeeeeeeeeeee eeeeeeeeeee eeeeeeeee eeeeeeeeee e eeeeeeeeeeeee eeee eee eeee eeeeeeeeeeee ee eee eeeeeeeee ee eee eeee-eeeeeeeeeeee eee eeeeeeeeeeeeee eeee (+)-eeeeeeee.

‌Meeeee 88‌ Meeeeeeee ee Meeeeeeeeeeeeeeeeee Meeeeeeee ee [8 + 8]-Meeeeeeeeee Meeeeeee ee Meeeeeee–Meeeeeeeeeeeee Meeeeeeee eee Meeeeeeeee Meeeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

8,8-Meeeeeeeeeeeee-8-eeeeeeeee Meeeeeeee ‌888‌; Meeeeee Meeeeeeee:[‌888‌]

MMMMMMM: Meeeeeeeeeee ee eeeeeeeee ee eeeee, eeeeeeee, ee eeee, eee ee eeeeee eeeee ee eeeeeeeeee.

Mee eeeee eeeeeeee (8.8–8 eeeee) eee eeeee eeeeeee e eeeeeee ee e eeee ee eeeeeee eeeeeee ‌888‌ (8 eeee) ee MMM (8 eM), eee eee eeeeeeeee eeeeeee eee eeeeeee ee ee (ee, ee eee eeee ee eeeeeeeeeeee, ee −88 °M) eeeee MMM eeeeeeee eeeeee eeeeeeee eeeeeeeeeeeee ee eee eeeeeeee eeeeeee. Meee, eeeeee eee (8.8 e) eee eeeee, eee eee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeee eeeeee eeeeeeeeeeeeee (eeeeee/MeMMe 88:8) ee eeee eee eeeeeee eeeeeeeee ‌888‌ ee eee eeee.

8,8-Meeeee-8-eeeeeeee[8.8]eeeee-8-eeeeeeeee Meeeeeeee ‌888‌; Meeeeee Meeeeeeee:[‌888‌]

M eeee ee eee Meeeeee eeeeeee(eeeeee)eeeeeee ‌888‌ (8 eeee) eee eee eeeeeee eeee eeeeeeeee ee ‌888‌ (8.8 eeee) ee eeeee MMM (88 eM) eee eeeee eeeeeeee ee e eeeeeeeeee ee eeeee MeM (888 ee, 8 eeee) ee eee MMM (8 eM) ee −88 °M eeeee ee eeeee eeeeeeeeee. Mee eeeeeeeee eeeeeeeeee eee eeeeeee ee −88 °M eeeee MMM eeeeeeee eeeeee eeeeeeee eeeeeeeeeee ee eee eeeeeeee eeeeeeee (8–88 e). Meeeee eee (8.8 e) eee eeee eeeee ee eee eeeeeee eee eee eeeeeee eee eeeeeee eeeee eeeeeee eeeeeeee. Mee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee/MeMMe 888:8 ee 8:8) eeeee M8. Meeeeeeeeeeeeeeeeee eeeeeeeee ‌888‌ eeee eeeeeeee ee eeeeee eeee.

References