Table 1.

Rhodium-Catalyzed Enantioselective Si–H Bond Insertions of Diphenyl Diazomethylenes D1–D12

entrya	R	Δσp (R-H)b	product	yield (%)	ee (%)
1	NO2	0.78	P1	92	>99
2	CN	0.66	P2	96	98
3c	CF3	0.54	P3	91	95 (S)d
4c	SCF3	0.50	P4	68	97
5c	OCF3	0.35	P5	66	76
6	Cl	0.28	P6	95	66
7	Br	0.23	P7	79	77
8	I	0.18	P8	62	82
9c	F	0.06	P9	88	25
10	Me	−0.17	P10	51	18
11	OMe	−0.27	P11	47	64 (R)d
12	NMe2	−0.60	P12	45	91

^aReaction conditions: Condition A (for entries 1–3, 6, 7, 10, and 11): diazo compound (0.2 mmol), PhMe₂SiH (1.2 equiv), C2 (0.1 mol %), DCM, 0 °C. Condition B (for entries 4, 5, 8, 9, and 12): hydrazone (0.2 mmol), MnO₂ (3.5 equiv), MgSO₄, DCM, rt, 5–6 h; then PhMe₂SiH (1.2 equiv), C2 (0.1 mol %), DCM, 0 °C. Isolated yields were given. The ee values were determined by chiral HPLC.

^bHammett substituent constant for para substituents.

^cThe ee value was determined by the corresponding alcohol obtained through the oxidation of the Si–H insertion product.

^dThe absolute configuration was assigned by analogy with the reported data (see Supporting Information for details).