6540
Acknowledgements
The author wishes to thank Dr Lawrence A. Reiter for helpful discussions and Drs Mikel P.
Moyer and Kelvin Cooper for their encouragement and support.
References
1. Carpino, L. A. J. Org. Chem. 1964, 29, 2820.
2. Chong, J. M.; Park, S. B. J. Org. Chem. 1993, 58, 7300.
3. To a suspension of 5.25 g of Wang resin (Polymer Labs, 1.7 mmol/g) in anhydrous dichloroethane (75 mL) at 0ꢀC
was added a solution of N-(chlorocarbonyl isocyanate (Aldrich, 5.0 g, 58 mmoles) in dichloroethane (10 mL). The
resulting mixture was gently stirred at rt for 7 h and re-cooled to 0ꢀC. A solution of tert-butanol (10 mL) and
DMAP (0.25 g) in dichloroethane (30 mL) and DIEA (20 mL) was added and the mixture stirred gently at rt for
48 h. The resin was collected by ®ltration, washed with DMF (2Â), THF (3Â), dichloromethane (2Â) and MeOH
(2Â) and dried at 50ꢀC in a vacuum oven for 24 h to give 6.4 g (99%) of 2. Nitrogen analysis indicated that the
loading of 2 was 1.5 mmol/g.
4. Prepared by NaBH4 reduction of commercially available 1,3-diphenyl-1-propanone.
5. Koch, K.; Smitrovich, J. H. Tetrahedron Lett. 1994, 35, 1137.
6. General procedure for the preparation of 1ꢀ amines: To a suspension of 2 (0.3 g, 0.45 mmols) in THF (4 mL) was
added alcohol (2 mmol, 4.5 equiv.) and triphenylphosphine (2.0 mmol). After shaking for 5 min, DEAD (2 mmol)
was added dropwise. The resulting mixture was shaken gently for 12 h, ®ltered and washed (DMF, THF and
MeOH). After drying under vacuum overnight, the resin was suspended in 1:1 TFA/DCE (3 mL), shaken for 4 h
and ®ltered. The ®ltrate was concentrated in vacuo and the crude amine was puri®ed by strong cation exchange
column (see Ref. 8 for the use of strong cation exchange column in puri®cation of amines) to give the desired
product 6a±b.
7. The stereochemistry of 6b was established as trans by the use of NMR coupling constants. (5.1 Hz for trans versus
3.1 for cis). The cis isomer was prepared from the corresponding trans alcohol (see Ref. 6 for the preparation of
the cis alcohol).
8. Lawrence, R. M.; Biller, S. A.; Fryszman, O. M.; Poss, M. A. Synthesis 1997, 553.
9. During the course of this work a solid-phase synthesis of primary amines using a resin bound phthalimide was
reported by Aronov and Gelb. Tetrahedron Lett. 1998, 39, 4947.