Table 1.

Synthesis of Tetrahydropyridines 3 From Ethyl 2-Methyl-2,3-butadienoate and N-Tosylaldimines^a

entry	R	product	yield (%)b
1	Ph (2)	3	94c
2	4-MeOC6H4 (2a)	3a	99
3	4-MeC6H4 (2b)	3b	95
4	3-ClC6H4 (2c)	3c	96
5	2-ClC6H4 (2d)	3d	93
6	4-FC6H4 (2e)	3e	95
7	4-NCC6H4 (2f)	3f	98
8	2-F3CC6H4 (2g)	3g	98
9	4-O2NC6H4 (2h)	3h	86
10	2-HOC6H4 (2m)	3i	0
11	2-TBSOC6H4 (2n)	3j	93
12	2-pyrrolyl (2l)	3k	0
13	N-Boc-2-pyrrolyl (2m)	3l	99
14	1-naphthyl (2i)	3m	96
15	2-furyl (2j)	3n	97
16	4-pyridyl (2k)	3o	92d
17	tert-butyl (2o)	3p	86e
18	n-propyl (2p)	3q	0f

^a1.0 mmol scale.

^bIsolated yields.

^c30 mmol scale.

^d30 mol% PBu₃ was used.

^e3 equiv of Na₂CO₃ was added.

^fThe imine decomposed to the corresponding aldehyde and p-toulenesulfonamide.