. Author manuscript; available in PMC: 2010 Oct 15.

Published in final edited form as: Org Lett. 2009 Oct 15;11(20):4520–4523. doi: 10.1021/ol9016595

Table 1.

Catalytic asymmetric Cr-mediated propargylations.^a



entry	R₁	sulfonamide	yield (%)^b	ee or de (%)^c
1a	-CH₂CH₂CH₂OTBDPS	E	78	90
1b	-CH₂CH₂CH₂OTBDPS	D	85	83

2a	-CH₂CH₂CH₂CH₂Me	E	82	81
2b	-CH₂CH₂CH₂CH₂Me	D	81	67

3a	-CH₂CH₂C₆H₅	E	91	89
3b	-CH₂CH₂C₆H₅	D	94	72

4a	CH₂CH(Me)CH₂CH₂CH=C(Me)₂-S	E	70	93
4b	CH₂CH(Me)CH₂CH₂CH=C(Me)₂-S	D	81	93

5a	-CH₂CH(Me)CH₂CH₂CH=C(Me)₂-R	E	73	80
5b	-CH₂CH(Me)CH₂CH₂CH=C(Me)₂-R	D	86	84

6a	-(CH₂)₆-c	E	67	78
6b	-(CH₂)₆-c	D	88	90

7a	-C(Me)₃	E	55	92
7b	-C(Me)₃	D	75	73

8a	-C₆H₅	E	80	46
8b	-C₆H₅	D	92	73

9a	-CH=CHC₆H₅-E	E	84	51
9b	-CH=CHC₆H₅-E	D	89	70

All reactions were performed with CrBr₃ (10 mol %), D or E (11 mol %) at 0 °C. Based on the previous examples,⁶ the absolute configuration of the major product was predicted as indicated and confirmed from the ¹H NMR analysis of Mosher esters.

Yields based on chromatographically isolated products.

Ee and de were estimated by ¹H-NMR analysis of its Mosher ester. For details, see Supporting Information.