Nature Communications

Table 1 Optimization studies for asymmetric Ugi and Ugi-azide reactions

From: Enantioselective Ugi and Ugi-azide reactions catalyzed by anionic stereogenic-at-cobalt(III) complexes


Entry	1	solvent	terminating reagents	6		7
Entry	1	solvent	terminating reagents	yield (%)^a	e.r.^b	yield (%)^a	e.r.^b
1	Λ-(S,S)-1a	toluene	5a	54	80.5:19.5	˗	˗
2	Λ-(S,S)-1b	toluene	5a	33	85.5:14.5	˗	˗
3	Λ-(S,S)-1c	toluene	5a	63	80.5:19.5	˗	˗
4	Λ-(S,S)-1d	toluene	5a	61	84.5:14.5	˗	˗
5	Λ-(S,S)-1e	toluene	5a	77	88.5:11.5	˗	˗
6	Λ-(S,S)-1f	toluene	5a	64	93:7	˗	˗
7	Λ-(S,S)-1g	toluene	5a	89	92:8	˗	˗
8	Λ-(S,S)-1h	toluene	5a	72	95:5	˗	˗
9	Λ-(S,S)-1i	toluene	5a	trace	N.D.	˗	˗
10	Λ-(S,S)-1j	toluene	5a	27	71:29	˗	˗
11	Λ-(S,S)-1k	toluene	5a	18	69:31	˗	˗
12	Λ-(S,S)-1l	toluene	5a	39	65.5:34.5	˗	˗
13	Λ-(S,S)-1m	toluene	5a	70	94.5:5.5	˗	˗
14	Λ-(S,S)-1n	toluene	5a	83	93.5:6.5	˗	˗
15	Λ-(S,S)-1o	toluene	5a	96	93:7	˗	˗
16	Λ-(S,S)-1p	toluene	5a	40	95:5	˗	˗
17	Δ-(S,S)-1b	toluene	5a	39	28:72
18^c	Λ-(S,S)-1h	toluene	5a	99	97.5:2.5	˗	˗
19^c	Λ-(S,S)-1h	CHCl₃	5a	25	76.5:23.5	˗	˗
20^c	Λ-(S,S)-1h	ⁿhexane	5a	38	94.5:5.5	˗	˗
21^c	Λ-(S,S)-1h	Et₂O	5a	25	95:5	˗	˗
22^c	Λ-(S,S)-1h	CH₂Cl₂	5a	29	69.5:30.5	˗	˗
23^d	Λ-(S,S)-1h	toluene	TMSN₃	˗	˗	76	94.5:5.5
24^d	Λ-(S,S)-1h	toluene	TsN₃	˗	˗	trace	N.D.
25^d	Λ-(S,S)-1h	toluene	NaN₃	˗	˗	trace	N.D.
26^d	Λ-(S,S)-1h	toluene	NaN₃ + MeNH₃⁺Cl⁻	˗	˗	79	93:7
27^d	Λ-(S,S)-1h	toluene	NaN₃ + 5b	˗^f	˗	65	95:5
28^e	Λ-(S,S)-1h	toluene	NaN₃ + 5b	˗^f	˗	82	95.5:4.5

Asymmetric Ugi-4CRs were performed by using 2a (0.12 mmol), 3a (0.10 mmol), 4a (0.12 mmol), 5a (0.10 mmol), 4 Å MS (100 mg) and 1 (0.01 mmol) in toluene (2.0 mL) at −20 °C for 48 h.
^aIsolated yields were based on 3a.
^be.r. values were determined by chiral stationary HPLC.
^c2a (0.15 mmol), 4a (0.30 mmol), and 5a (0.50 mmol) were employed at −40 °C for 24 h.
^dAsymmetric Ugi-azide reactions were performed by using 2a (0.15 mmol), 3a (0.10 mmol), 4a (0.30 mmol), terminating reagents (0.30 mmol), 4 Å MS (100 mg) and Λ-(S,S)-1 (0.01 mmol) in toluene (2.0 mL) at −20 °C for 48 h.
^eNaN₃ (0.30 mmol) and 5b (0.40 mmol) were employed at −30 °C.
^fA little amount of Ugi-4CR product (11% and 13% yield, respectively) was formed. N.D. = not detected.

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