Table 1 The effect of temperature, concentration, ligands, and solvents on the asymmetric allenylation of pyrazolone 2a with allene 1a^a.


Entry	ZYC-Phos	Solvent (v)	Yield (ee) of (S)-3aa/4aa/1a recovered (%)^b
1^c	DACH-ZYC-Phos-C2	CHCl₃ (3)	14 (85)/trace/67
2	DACH-ZYC-Phos-C2	CHCl₃ (3)	75 (87)/4/6
3^d	DACH-ZYC-Phos-C2	CHCl₃ (3)	80 (86)/4/0
4^e	DACH-ZYC-Phos-C2	CHCl₃ (1.5)	67 (82)/7/4
5^e	DACH-ZYC-Phos-C2	CHCl₃ (5)	78 (87)/3/4
6^f	DACH-ZYC-Phos-C2	CHCl₃ (10)	70 (88)/2/12
7	DACH-ZYC-Phos-C2	CHCl₃ (10)	76 (89)/2/17
8	DADPE-ZYC-Phos-C2	CHCl₃ (10)	79 (79)/5/8
9^g	DACH-ZYC-Phos-C3	CHCl₃ (10)	84 (76)/7/0
10	DACH-ZYC-Phos-C1	CHCl₃ (10)	79 (90)/2/10
11^h	DACH-ZYC-Phos-C1	Toluene (10)	100 (95)/0/0
12	DACH-ZYC-Phos-C1	THF (10)	92 (83)/3/0
13	DACH-ZYC-Phos-C1	CH₃CN (10)	23 (n.d.)/4/60
14	DACH-ZYC-Phos-C2	Toluene (10)	87 (96)/0/11
15	DACH-ZYC-Phos-C3	Toluene (10)	90 (87)/0/0

^aReaction conditions: 1a (0.2 mmol), 2a (1.2 equiv), Pd₂(dba)₃•CHCl₃ (2.5 mol%), and ligand (6 mol% for entries 1–6; 5 mol% for entries 7–13) unless otherwise noted. ^bThe yields of (S)-3aa and 4aa as well as the recovery of 1a were determined by the ¹H NMR analysis of the crude product using mesitylene as the internal standard and the ee of isolated (S)-3aa was determined by chiral HPLC. ^cAt 30 °C for 20 h. ^dAt 80 °C. ^eThe reaction time was 14 h. ^fThe reaction time was 16 h. ^gThe reaction time was 12.5 h. ^hThe reaction was conducted on 0.5 mmol scale. Cbz benzyloxycarbonyl, THF tetrahydrofuran.

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