Table 1.

Preparation of compounds 3 by one-pot CEYM–Diels–Alder reaction of substrates 1 (method A).

entry	1	R1	dienophile	product	% yield method Aa (time, h)	% yield method Bb (time, h)
1	1a	Bn–NH		3a	60 (2 h)c	–
2	1a	Bn–NH		3b	55 (8 h)	70 (20 h)
3	1a	Bn–NH		3c	51 (6 h)	55 (6 h)
4	1a	Bn–NH		3d	50 (4 h)	63 (24 h)
5	1a	Bn–NH		3e	47 (24 h)	50 (24 h)
6	1a	Bn–NH		3f	85 (120 h)c	–
7	1b	(R)-Ph(Me)–CHNH		3g + 3g’	87 (4 h)d	73 (24 h)d
8	1b	(R)-Ph(Me)–CHNH		3h + 3h’	74 (2 h)d	70 (10 h)d
9	1b	(R)-Ph(Me)–CHNH		3i + 3i’	74 (20 h)c,d	–
10	1b	(R)-Ph(Me)–CHNH		3j	63 (10 h)	60 (24 h)
11	1c	PropylNH		3k	40 (5 h)	–
12	1d	Ph		3l	48 (4 h)	55 (15 h)
13	1d	Ph		3m	28 (8 h)	–
14	1d	Ph		3n	58 (12 h)	70 (17 h)
15	1e	Cy		3o	54 (12 h)	–

^aMethod A: One-pot protocol with Mori´s conditions. The formation of the corresponding diene 2 with ethylene was complete after 2 h at 90 °C for all substrates. ^bMethod B: Tandem multicomponent protocol mediated by 1,7-octadiene [29]. ^cWhen maleic anhydride or 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione were used as dienophiles, the Diels–Alder reaction was performed at rt. With maleic anhydride final products were isolated as the corresponding diacid derivatives. ^dIn all cases, adducts were obtained as an inseparable 1:1 mixture of diastereoisomers.