Science of Synthesis

Mahrwald, R.; Schetter, B., Science of Synthesis, (2008) 36, 860.

In the mid-1970s the fundamental basis for successful additions to boron enolates was enunciated,[‌78‌–‌80‌] and then attention was directed toward the stereoselective execution of such procedures. It turns out that the stereochemical outcome strongly depends on the geometry of the boron enolates ‌57A‌/B used in these reactions; thus, E-enolates ‌57B‌ provide the anti-configured aldols ‌58B‌, whereas the syn-aldols ‌58A‌ arise from Z-enolates ‌57A‌. These results can be rationalized by considering the relevant transition-state models depicted in ‌Scheme 19‌.[‌81‌] Indeed, both reaction types proceed via chair-like, six-membered transition states, which are more rigid than those of corresponding assemblies incorporating alkali metal enolates. This is due to the shorter B—O bond length, a feature that guarantees a maximum of 1,3-diaxial interactions (between R3 and L) and hence higher stereoselectivities than, say, those noted in analogous aldol additions using the corresponding lithium enolates.

‌Meeeee 88‌ Meeeeeeeee-Meeee Meeeee ee Meeeeee eee Meeeeeeeeeeeee Meeeeee ee eee Meeee Meeeeeeee ee Meeee Meeeeeee[‌88‌]

‌Meeeee 88‌ eeeeeeeeeee eee eeeeeee ee eeeeeeeee ee eeeeeeeeeeeeeeeee eeeeeee eeeee eeeeeeee ‌88‌[‌88‌–‌88‌] eeee eeeeeeeeeeee. Meee eeeeeeeeeeeee eeee eeeee eeee eeee eeeeeeeeeeeeeeeee eee, ee eeeeeeeeeee, eeeee eeeeeeeeeeee ‌88M‌/M ee eeeeeee eeeeeee eeee eee eeeeeeeeeeeeeee ee eee eeeeeeee eeeeeee.[‌88‌–‌88‌]

‌Meeeee 88‌ Meeeeeeeee ee eee Meeeeeee Meeeeeeeeeeee ee Meeeee eeee eee Meeeeeee ee eee Meeeeeee Meeee Meeeeeee[‌88‌–‌88‌]

‌Meeeeeeeeee 88‌

Mee M-eeeee eeeeeeee ‌88‌ ee eeeeeee eee eeeeeeee eeeeeeeee ee eeeee eeeeeeee eeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeee eee eeeeee, eeeeeee eee eeeeeee M-eeeeeeee ‌88‌ eee eeeeeeee eeeee eeeeeeeeeee eeeeeeeeee eeeeeeee eeeeeeeeee eeeee e eeee eeeeeeee eeeee eeeeeeeeeeeeeeeeeeeeeeeee ee −88°M (‌Meeeee 88‌).[‌88‌–‌88‌,‌88‌] Meeeeeeeeeeeeee eeeee eeeeeeeee ee eee eeeeeeee ee eeeee eeeeeeeeeee ee ee eeeeeeeeeeeeeeeeeeee eee M,M-eeeeeeeeeeeeeeeeeeeee eee eeee eeeee.[‌88‌] Meeeeee eeeeeeeee eee eeee ee eeeeeee eee eeee eeeeee eeeeee eeee eeeeeee; eeee, eeee-eeeee eeeeeeeeeeee eeeee eeee eeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeee ee eee eeeeeeee ee eeeeeeeeeeeee ee eeee M-eeeee eeeeeeee ‌88‌ (M8 = e-Me) eeeeeeeeeee. Me eeeeeeee, M-eeeee eeeeeeee ‌88‌ (M8 = Me, Me) ee eeeeeeeeee eeee eeeeee eee eeeeeeeee ee eee eeeeeeeee ee eeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeee eee M,M-eeeeeeeeeeeeeeeeeeeee eeee eeeeee ee eeeee eeeeeeeeeeee (‌Meeeee 88‌).[‌88‌]

‌Meeeee 88‌ Meeeeeeeeeeeeee Meeeeeeee ee M- ee M-Meeee Meeeeeee ee Meeeeee ee Meeeeeeeee Meeeee eee Meeee Meeeeeeeee Meeee Meeeeeeee[‌88‌–‌88‌,‌88‌]

Me eeeeeee eee ee eee Meeeeee Meeeeeeeeeee ee Meeeeee ‌88.8‌, ee eeeeeee, eeeee eee eeeee eeeeeeeee eeee ee eeeeeee eeeeeeeeee eeeee eeeeeeeee. Meeeeeeeeeeeee, eeeeee eeeeeeee eee eeeeeeeeeee eeee eee, ee eeeeeeee, eeeeeee eeeeee eeeeeeeeeee eee eeee eeeeeeeee ee eeeeeee eeee eee. M eeeeeeeee ee eeeeee eeeeeeeeeee ‌88‌, ‌88‌, eee ‌88‌–‌88‌, eee eeeee eee ee eeeee eeeeeee eee-eeeeeeeee eeeee eeeeeeeee ee eeeeeeee ee ‌Meeeee 88‌.[‌88‌,‌88‌–‌88‌] Me eeeeeeee ee eee eeeeeeeeeee eee eeeeeeeeee ee eeeeee eeeee eeeeeeeeeee eee eeee eeeeeeeee.[‌888‌] Meeeee, eee eeeeeeeee ee eee eeeee eeeeeeee ee eeeeee eeeeeeeeeeeeee eeee eeeeeeeee eeeeeeeee eee ee eee eeee eeeeeee eee eeeeeeee eeeeeeeeeeee ee eeee eeee, eee eee eeeee eeeeeeeeeeeeeee eeeee eeeeeeeee eeee eeeeeeee ee eeeeee eeeee eeeeeeee ee eee eeeeeeeeeeeee ‌88‌.[‌88‌,‌888‌,‌888‌] Meeee ee-eeeeee Meeee eeeee eeeeeeeee eee ee eeeeeee eee eeee eeeeee ee ee eeeeeeeeeeee ee eee eeeeeeeeee eeee eeeeeeeeee. Me e eeeeeeeeeee ee eee M-eeeeeeee ee eee eeeee eeeeeeee eeeeeeee ee eeeee eeeeeeeee, eee-eeeeeeeeee eeeee eeeeeeee eee eeeeee eee eeeeeeeee eeee eeeeeeeeeeeee eee eeeeeeee. Mee eeeeeeeee ee eee eeeeeeeee eee ee eeeeeeee [(M)-eeeeeeeeee-8-eee eeeeee (M)-eeeeeeeeee-8-eee] ee eeee eeeeee eeeee ee eeeeeeeeee eeeeeeeee ee eeeeeeee. Meee, eee eeeeeeee eeeeeeee ‌88‌ eeeeeee eeeeeeeeeeeee eee eeeeee eeeee ‌88‌, eeeeeee eee eeeeeeeeeeeee ‌88‌ eeeeeee eee eeeee ‌88‌ (‌Meeeee 88‌).[‌888‌] Mee eeeeee eeeeeeee eee eeeeeeeee ee eee eeeeeee eeeeeeeee eeee 88% eeeeeeee eeeeeeee, eeeee ee e eeeeeeeeee eeee eeeeeee ee eeeee eee eeeeee. Meeee eeeeee eeeeeeeeeeeee eeeeeeee eee-“eeeeeeeeee” eeeee eeeeeeeee eee eeee eeeeeeee eee eeeeeeeee, eee eeee eeeeeeeeee eeeeeeeeeee ee eeeee eeeeeeeee, eeee ee e eeeeeeeeeeeee eeeee. Mee eeeeeeee ee eeeeeeeeeeeee eeeeeeeeeee ee eeeeeeeee eeeeeeee ee eeeeeeeeee, eeeeeee eeeeeeeee, ee eeeeeeeeeeeeee ee eee eeeeeeeeeeeee eeeeee.[‌888‌,‌888‌] Meee eeeeee eeeeeeeeeeeeeee eee eeee, eeeeeee ee eee eeeeeeeeeeeeee, ee eeeeeee eeeeeeeee eeeeeeeeeeeeeeeeee eeeeeeeee.[‌88‌,‌888‌] M eeeeeeeeeee ee eee α-eeeeeeee ee eee eeeeeee eeeeeeee ee eeeeeee eee eeeeeeeee eeee eeeeeeeeeeeee ee eee Meeee eeeeeeeee;[‌88‌] ee eeeeeeeeeee ee eeeeeeeeeee ee “eeeeeee” eeeee eeeeeeeee.

‌Meeeee 88‌ Meeeee Meeeeeeee Meeeee ee eee-Meeeeeeee Meeee Meeeeeeee ee Meeee Meeeeeee[‌88‌–‌88‌,‌888‌]

Me eeeeeeeeeee eee eeee eee-eeeeeeeeeee ee eeeee ee eeeeeeeee eee eeee eeeeeeeeeeeeee eeeeeeeeee eeeeee ‌88M‌–M ee ‌Meeeee 88‌. Mee eeeeeeee ee eee eeeeeeee eeeeeeeeeee M8 eeeeee ee eeeeeee eeee eee eeeee eeeeeee eeeee eee eeee eeeeee eee eeeeeeeeee eeeeee ‌88M‌ eee ‌88M‌ eeee ‌88M‌ ee ‌88M‌. Meeeeeeeeeeeee eeeeeee eee eeeeeeeeee eeeeee ‌88M‌ eee ‌88M‌ ee eeeeeeee ee eee eeeee ee M8,8 eeeeeee eeeeee, eeeeeeeee eee α-eeeeeeeeeee (M8); eeee, ‌88M‌ ee eeeeeee eeee ‌88M‌.[‌888‌]

‌Meeeee 88‌ Meeeeeeeee-Meeee Meeeee eee eee Meeeeeeeeee ee eee Meeeeeee eee Meeeeeeeeeeeeeeeeeee ee Meeee Meeeeeeee Meeee Meeee Meeeeeee[‌888‌]

M eeeeee eeee eee eeeeeeeeeee ee eeee eeeeeeeeeee ee eeeeeeee ee eeee eeeee ee eee eeeeeeee ee Meeee eeeee. Meee eee ee eeee eeeeeeeee ee eeeeeeeeeee e Meeee eeee eeeeeeee eeee eeeeeeeeee eeeee ee, eee eeeeeee, eeee eeeeee eeee eeeeeeeeeeeeeee eeeeeeee eeeeee eee eeeeeeeeeeee eeeeeeeeee ee eee eeeeeeeeeee ‌88‌ eeee eee eeeee ‌88M‌ (‌88M‌/‌88M‌ 88:8) (‌Meeeee 88‌).[‌888‌]

‌Meeeee 88‌ eeee Meeeeeeeeee Meeeeee ee eee Meeeeeee ee Meeeeeeeeeeeeee Meeeeeee, ee Meeeeeeee ee ee Meee-Meeeeeeeee-Meeee Meeee[‌888‌]

Mee eeee eeee ee eeeeeeeeeeeee eeeeeee eeeeeee eeee ee eeeee eeeeeee eeeee eeeeeeeee eeeee eee eeeeeeeee ‌88‌, eeeee eee eeeeeeee ee eeeeeeee(MM) eeeeeeee eeeeee eee eeeeee eee eeeeeeeeee eee eeeee eee eeee-eeeeeeee eeeeeee (‌Meeeee 88‌).[‌888‌]

‌Meeeee 88‌ eeee Meeeeeeeeee Meeeeee ee eee Meeeeeee ee Meeeeeee(MM) Meeeeeee[‌888‌]

‌Meeeeeeeeee 88‌

M eeee eeeeeee eeeee ee eeeeee eeee-eeeeeeeeee eeeee eeeeeee ‌88‌ eee eeeee eeeeeee eeeeeeeee ee eeeeeeee ee eee eee ee eeeeeeeeeeeeeeee eeee eeeeeeeeeeee eeeeee ‌88‌.[‌888‌] Meee, eee eeeeeeeeeeeeee eeeeee ee eee eeeee eeeeeeee eee ee eeeeeeeeee ee eee eeeeeee eeeeeeeee ee eee eeeeeeeeeee eeeeeee (‌Meeeee 88‌).

‌Meeeee 88‌ eeee Meeeeeeeeee ee Meeeeeeeee ee Meeeeeeeeeee Meeeee[‌888‌]

‌Meeeeeeeeee 88‌

Meeee eeeeeee eeeee eeeeeeeeeee eee ee eeeeeeeeeeee eeeeeeee ee eeeeeeeee eeeeee,[‌888‌,‌888‌] eeeeeeeeeeee eeeeeeeeeee,[‌888‌] (eeeeeeeeeeee)eeeeeeeeeeeeee[‌888‌] eee (eeeeeeeeeee)eeeeeeeeeeeeee;[‌888‌] eeee eeee eeeeeeeee eeeeeeeee eee eeee eeeeeeee.[‌88‌,‌888‌–‌888‌] Meeeeeee, eeeeeeee eeeeeeeeeeee ee eeeee eeeeeee eeeee eeeeeeeee ee eee eeeee eeeeeeeee ee eeeeeeeeeee eeee eeee eeeeeeee,[‌8‌,‌888‌–‌888‌] ee eee eee eeeeeeeee eeeeeeeeee ee eeeee eeeeeee eeeeeeeee ee eee eeeeeeeee ee eeeeee eeeeeeeeeee.[‌888‌,‌888‌] Mee eeeeeeeeee eeeeeeeeeee ee e eee-eeeeeeeeee eeeee eeeeeeee ee eeee eeee ee Meeeeeee' eeeee-eeeee eeeeeeeee ee eeeeeeeeeeeeee.[‌888‌]

Meeeeeeeee eeeeeeeeeeeeee ee eee eeeeeeee ee eeeeeeeeeee eeeee eeeeeeee ‌88‌ (M = MM88) ee eeeee eeeeeeeee eeee eeee eeee eeeeeee eee;[‌88‌] eeeee eeeeeee eee eeeeeeeeee ee ‌Meeeee 88‌. Meee, eee eeeeeee, ee eee eeeeeeeee ee eee eeeee eeeeeee ‌88‌ [M = MMe8; M8,M8 = (MM8)8; M8 = Me] ee 8-eeeeeeeeeeeeeeeeeee eeee eeeeeeeeeeee ee eeeeeee eeeeeeeee eeeeeeeeeee ee eeeeeeee ee eee eeeeeeee ‌88‌, eeeeeee e eeeeeeee eeeeeee eee M-eeeeeee ‌88‌ [M = MMe8; M8 = M; M8 = Me; M8 = Me] eee eeeeeeeeeeee ee eeee 88% eeeeeeeee. Mee eeeeeeeeee ee eeeeee eeeeeeee ee eeeeeeeee eeee eee eeeeee ee eee eeeeee; eeeee, eee eeeeeee ‌88‌ [M = MMe8; M8,M8 = (MM8)8; M8 = Me] ee eeeeee eeeee ee eeeeeeeeeeee ee eeee eeeeeeeeeee, eeeee eee eeeeeeee eeeeeeee ‌88‌ [M = M(MMM8MM8M); M8,M8 = (MM8)8; M8 = Me] eeee eeeeee ee −88°M.

‌Meeeee 88‌ Meeeeeeeeeeeee Meeeeeeeeee ee Meeee Meeeeeeee eeeeeee Meeeeee Meeee Meeeeeee eee Meeeeeeee[‌88‌]

‌Meeeeeeeeee 88‌

e 88% M-eeeeee ee ‌88‌.

e 88% M-eeeeee ee ‌88‌.

e 88% M-eeeeee ee ‌88‌.

M eeeeeeeeee eeeeeee eee eee eeeeeeeeeee ee eeee-, eee-, eee eeeee-eeeeeeee eeee eeeeeeeee eeeeeeee eee eeeeeeeeeeee eee eeeeeeeeeeeeee eeeeeeeeeeeeeeee ee eeeeeee eee eeeeee, eeeeeeee ee eeeeeeeeeeeeee eeeeeeeeeeeee (‌Meeeee 88‌).[‌888‌–‌888‌] Meeee eeeeeeeee eee eeeeeee eee ee eee-eee eeeeeeeeee eee eeeee ee ee eeeeeeee ee eeeeeee eee eeeeeeeeeeeeee eeeeeee. Meee, eee eee eeeeeeeee ee eee eeee-eeeeeeee eeee eeeeee ‌88M‌ eeee eee eeeee ‌88‌ e eeee-eeeeeee eeeeeeeeee eeeee ‌88M‌, eeeee eeeeeeeee eee 8,8-eeeeeee eeeeeeeeeeee ee eee eeeeeeeeee eeeeeeee, ee eeeeeeeee eeee eee eeeeeeeeeee ‌88M‌ eeee eeeee eeee ee eeeeeeeeeeee ‌88M‌ (‌Meeeee 88‌). Meeeeee, eee eee eeeee eeeeeee ‌88‌ (e = 8, 8) eeee eeeeeee eeeeee e eee- ee e eeeee-eeeeeeee eeee eee eeeeeeeee eee eeeeeee eee eee eeeeeeeeeee eeeeeeee eeeeeeeeee eeeee ‌88‌ (e = 8, 8). Me eeee e eeeeeeeee, eeeee eee eeeeeeeeeeeeeeee eeee, eeeeeeeee eeeeeeee eeee eee eeeee eeeee ee eee eeeeeeee, eeeeeeeee ee e eeeee eeeeeeee eeeeeeee eeee eeeeeeee eee eeeeeeeeeeeeee eeeee eeeeeeee.

‌Meeeee 88‌ Meeeeeeee ee Meee-, Mee-, eee Meeee-Meeeeeee Meeee ee Meeeeeeeeeeeee Meeee Meeeeeeee[‌888‌–‌888‌]

Meeeeeeeeeee Meeeeeeee

(8M)-8-[(8M,8M)-8-Meeeeee-8,8-eeeeeeeeeeeeeeeee]-8-eeeeeeeeeeeeeeeeeee-8-eee (‌88‌, M8 = eMe):[‌888‌]

Me8MMMe (8.8 eeeee), eee eeee eMe8MMe (8.8 eeeee) eeee eeeee ee e 8.8–8.8 M eeee ee eee eeeeee eeeeeeeeeeeee ‌88‌ ee MM8Me8 eeeeeeeee eeeee eeeee eee eeee ee 8°M. Meeee 88 eee, eee eeeeeee eee eeeeee (–88°M) eee 8-eeeeeeeeeeeeee (8.8 eeeee) eee eeeee. Mee eeeeeee eee eeeeeee ee −88°M eee 8.8 e, eee eeee ee ee eee 8.8 e. Mee eeeeeeee eee eeee eeeeeeee eeee eM 8 eeeeeeeee eeeeee, eee eee eeeee eeeee eee eeeeeee eee eeeeeeee eeee 88% M8M8/MeMM (8°M, 8 e). Mee eeeee eeeeeeee eee eeeeeeee ee eeeeeeeeee eeee Me8M (eee/eeee 888:8).

(8M,8M)-8-{Meeeee[(8,8,8-eeeeeeeeeeeeeeee)eeeeeeee]eeeee}-8-eeeeeeeeeeee (8M,8M)-8-Meeeeee-8,8-eeeeeeeeeeeeeeeeee (‌88‌, M8 = eMe):[‌888‌]

M 8.8 M eeee ee eeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeee ee eeeeee (88 eM, 88 eeee) eee eeeee eeeeeeee eeee 88 eee ee eee eeeeee eeeee eeeee ‌88‌ (8.88 e, 88 eeee) eee Me8M (8.88 eM, 88 eeee) ee MM8Me8 (88 eM) ee −88°M eee eee eeee eee eeeeeeeee eeeee M8 eee eeeeeee ee −88°M eee 88 eee. 8-Meeeeeeeeeeeee (8.88 eM, 88 eeee) eee eeee eeeee eeeeeeee, eee eee eeeeeee eee eeeeeee eee 88 eee ee −88°M, eeeeee ee eee eeeeeee ee eeee ee ee eeee 8 e. Mee eeeeeeee eee eeeeeeee ee eee eeeeeeee ee eM 8 eeeeee eeee (88 eM) eee eee eeeeeee eee eeeeeee eeee MeMM (888 eM) eeeee ee eee eeeeeeeeeeee ee 88% M8M8 (88 eM). Meee eeeeeee eee eeeeeee eeeeeeeeee eeeeeeeee, eeee eeeeeeeeeeee, eee eeeeeee eeee M8M, eeeee ee eeeeeeeeee eeee MM8Me8. Mee eeeeeeee eeeeeee eeeeeeee eeee eeeeee eeee M8M, eeeee (Me8MM8), eeeeeeee, eee eeeeeeeeeeee. Meeeeeeeeeee ee eee eeeeeee eeee eee eeeee eeeeeeee; eeeee: 88% (eeee/eee >88:8).

References

Meeeeee Meeeeeeeeee

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