Table 2 Substrate-controlled Co-catalyzed asymmetric Mukaiyama hydration of 9 in batcha

From: Flow chemistry-enabled asymmetric synthesis of cyproterone acetate in a chemo-biocatalytic approach

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Entry

Co catalyst

(mol%)

Solvent

Yield

(%)b

Entry

Co catalyst

(mol%)

Solvent

Yield

(%)b

1

Co(acac)2 (3.0)

THF

56

7

CoBr2 (3.0)

EtOH

N.D.

2

Co(acac)2 (3.0)

MeOH

N.D.

8

Co(OAc)2 (3.0)

EtOH

N.D.

3

Co(acac)2 (3.0)

DCM

44

9

Co(acac)3 (3.0)

EtOH

24

4

Co(acac)2 (3.0)

DCE

40

10

Co(acac)2 (2.0)

EtOH

95 (82)c

5

Co(acac)2 (3.0)

EtOH

94

11

Co(acac)2 (1.0)

EtOH

88

6

CoCl2 (3.0)

EtOH

N.D.

    
  1. a Unless otherwise noted: reactions were performed using 9 (0.3 mmol, 1.0 equiv.) in EtOH, Co(acac)2 (X mol%) and PhSiH3 (2.0 equiv.) at 25 °C for 6 h under 1 atm of oxygen.
  2. b Determined by LC-MS.
  3. c Isolated yield.
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