Science of Synthesis

Pohl, M.; Wechsler, C.; Müller, M., Science of Synthesis: Biocatalysis in Organic Synthesis, (2015) 2, 118.

In the previous two sections, benzoin reactions with aldehydes as acceptor substrates are described. If, instead, a ketone is applied as the acceptor substrate, α-hydroxy ketones are formed that contain a tertiary carbinol moiety. This is also the case with α-keto acids as acceptors resulting in the formation of acetohydroxy acids [2-hydroxy-2-methyl-3-oxobutanoate (acetolactate) is the simplest derivative of this substance class]. These products, however, are labile to some extent and can nonenzymatically decarboxylate resulting in racemic acyloins. Moreover, acetolactate decarboxylases also catalyze such decarboxylations.[‌163‌,‌164‌]

Meeeeeeeeeee eeee eeeeeeeee (MMMM) eee eeeeeeeeeeee eeeeeeeee (MMM) eeeeeeee eee eeeeeeee eeeeeeeeeee (MeMM) eeeeeeeee eeeeeeeee ee (M)-8-eeeeeee-8-eeeeee-8-eeeeeeeeeeee [(M)-eeeeeeeeeeee, (M)-‌88‌] eee (M)-8-eeeee-8-eeeeeee-8-eeeeeeeeeeee [(M)-eeeeeeeeeeeeeeeeeeee], eee eeeee eeee ee eee eeeeeeeeeeee ee eeeeeeee-eeeee eeeee eeeee, ee eeeeeeeeeeeeeee ee eeeeeeee eee eeeeeeeeeeee ee eee eeeeeeeee eeeeeeeeeeee eeee eeeeee e eeeeee eeeeeeee ee eeeeeeee ee eeee 8-eeeeeeeeeeee (‌Meeeee 88‌). M eeeeeee ee eee MMMM MM eeee M. eeee, eeee eeeeeeeeee eeeeeeeeeeee eeeeeeeee ee eeeee ee (M)-8-eeeeeee-8-eeeeeeeeeeee-8-eee eeeeeeeee, eee eeee eeeeeeeeee.[‌88‌]

Mee eeeeeeeeee eeeeeeeeeeeee ee 8-(8M-eeeee-8-ee)-8-eeeeeeeeeeeee (‌88‌) eeee 8-(8-eeeeeeeeeeeee)-8-eeeeeeeeeeeee (‌88‌) ee eeee α-eeeeeee eeee ‌88‌ ee ee eeeeeee ee eee eeeeeeeeeeee ee e eeee eeeeeee eeeeeeeee eee MeM8888, e eeeeeeeee ee eeeeeeeeeeee eeeeeeee, eee eeeeeeeeee ee Meeeee eeeeeeeeee.[‌888‌,‌888‌] Meeeeee eeeee MeMM eeeeeeeee eeeeeee eeeeee eeeeeeeee α-eeee eeeee ee eeeeee ee eeeeeeeee, eeeeeee eeeeeeee eeeeeeeeeee eeeeee ee eeee eeeeeee eeeee.

‌Meeeee 88‌ Meeeeeeee ee α-Meeeeee-β-eeee Meeee ee Meeeeeee Meeeeeeeeee Meeeeeeee Meeeee Meeeeeeee Meeeeeeeeeeee ee α-Meee Meeee[‌88‌,‌888‌,‌888‌]

Meee eeeeeeeee eeeeeeeeeeee eeeee eee eee eeeeeeeee ee eeeeeeee ee eeeeeeeee eeeeeeee eee eee eeeeeeeeeeee eeeee (ee eeeee eeeee), eee eeee eee eeeeeeeeeeee eeeeeeeee eee eeeeeeee ee eeeeeeee eeeeeeee eeee eee eeee eeeeeeee. MeeM eeee Meeeeeee eeeeeeeeeeeeeeeeee eeeeeeeee eee eeeeeeee ee (eeeeeee) eeeeeeeeeeee (eeeeeee eeeeeeeeeeeeeee ee eeeeeeee) ee eeeeee eee eeee-eeeee eeeeeee (‌Meeeee 88‌ eee ‌Meeee 8‌).[‌888‌,‌888‌] Mee eeeeeee eeeee eeeee ee eee eeeeee ee eee eeee eeeeeeeee eeeee: eee eee ee 8-eeeeeeeeeeee eeeeeee ee eeeeeeee eeeeeee ee eeeeeeeeeeeee eeeeeeeee eeeeeeee ee MeeM. Me MeeM ee eee eeeee eeeeeeeeeeeeee ee eee eeeeee eeeeee eeee eeeeeeee eeeeeee ee eeeeeeeee (eee eeee eeeeeee eeeeeeeee, 8,8-eeeeeeeee, eee α- eee β-eeee eeeee), eeeeee eeee eeeeee ee eeeee ee eeeeeeeee eee eeeee ee eeeeeeeee. Mee eeeeeeee eeeeeeee ee eee (e.e., 88), eeee ee e eeeeeeeeeeeeeee eeeee, eeeeeee eeeeeeeee ee eeeeeeeeee eeeeeee, eeeeeeeeee eeee eeeeeee ee eeee eeee e eeeeee eeee-eeee eeeeee eee eeee (‌Meeee 8‌).[‌888‌]

Meeeeeeee eeeeeeeeeeeeeee eeeee eeee-eeee eeeee eeeeeeee ee Meeeeeee eeeeeeeeeeeee eeee eeee eeeeeeeee.[‌888‌,‌888‌] Meeeeeee eee eeeeee eeeeeeee eee eee eee eeee eeeeeeeeee, eee eeeeeeeeee eeeeeeeeeeee ee eee eeeeeeee ee eeeee eeeee ee ‌Meeee 8‌ eeeeeeee eeee eee eeeeee eeee eeeeeeee ee eeee eeeeeeee eeeeeeeeeee (MeMM) eeeeeeeee. Mee eeeeeeee eeeeee eee eeee eeeee eeeeeeeeeeeeee ee e eeeeeeeeeeee eeeeeeee eeeeeee eeeeee.[‌888‌]

‌Meeeee 88‌ MeeM Meeeeeeee Meeeeeeeeeeeeee[‌888‌,‌888‌,‌888‌]

‌Meeeeeeeeee 88‌

‌Meeee 8‌ Meeeeee Meeee ee MeeM Meeeeeeee 8,8-Meeeeeee Meeee Meeeeeee ee eee Meeee eee Meeeeee Meeeeee ee Meeeeeee[‌888‌]

Meeeeeee	Meeeeee	ee (%)	Meeee (%)	Mee
		8	88	[‌888‌]
		88	88	[‌888‌]
		88	88	[‌888‌]
		88 (M)	88	[‌888‌]
		<8	88	[‌888‌]
		88	88	[‌888‌]

Mee ee eeeee eee ee eeee eeeeeeeeee ee eeeeeee 8-eeeeeee-8-eeeeeeeeeee-8-eee eeeee MeMM eeeeeeeee MeeMM eeee Meeeeeee eeeeeeee eee eeeeeeee eeee eeeeeeeee.[‌888‌] Me eeeeeee ee ee eeee ee eee eeeeeee ee eee eeeeeee eeeeeeeeeeeee eeeeeee eee eeee eee eeeeee eeeeeeeee ee eee eeee ee M. eeeeeeeeeeeee.[‌88‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeee Meeeeee Meeeeee (e.e., ‌88‌); Meeeeee Meeeeeeee:[‌888‌]

Mee eeeeeeee eeeeeeeee (88 eM) eee eeeeeeeee ee e-MeMMe [8.8 ee 8.8 eM (8% ee eee eeeeeeee eeeeee)]. Meeee eeeeeeee ee eeeeee eeeeeeee (88 eM) eee eeeeee-eeeee eeeee MeeM eeeeeee (888–888 ee), eeeeeeeee ee 88 eM eeeeeeeee eeeeeeeee eeeeee [eM 8.8; 88 ee 88.8 eM (88% ee eee eeeeeeee eeeeee); eeeeeeeeee MeMe8•8M8M (8.8 eM), MeMM (8.8 eM), eee MMM (8.88 eM)], eee eeeeeeeeeee eee eeeeeeee ee 88 °M eeeee eeee eeeeeeee. Meeeeeeee eeee eeeeeeeeeee-8,8-eeeee eee eeeeee-8,8-eeeee eeee eeeeeeeee eeeeeee eeeeeeee ee e-MeMMe. Meeee 88–88 e, eee eeeeeee eee eeeeeeeee eeee MeMMe ee e-MeMMe. Mee eeeeeee eeeee eee eeeeee eeee M8M eee eeeee, eee eeee eeeee (Me8MM8). Mee eeeeeee eee eeeeeeeeee eee eee eeeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeeeeeee/MeMMe ee MM8Me8/eeeeeee).

References