Table 1. Preparation of Sulfonamide-Incorporated α-Aminophosphonates 20–34^a.

compd	R	yield (%)b	compd	R	yield (%)b
5	4-Me	71	20	4-Me	56
6	4-Ph	24	21	4-Ph	41
7	4-OMe	66	22	4-OMe	51
8	4-SMe	43	23	4-SMe	60
9	4-F	84	24	4-F	67
10	4-Cl	69	25	4-Cl	66
11	4-Br	58	26	4-Br	45
12	3-F	75	27	3-F	37
13	3-Br	87	28	3-Br	31
14	2-F	65	29	2-F	57
15	2-NO2	41	30	2-NO2	42
16	2-OMe-6-Br	93	31	2-OMe-6-Br	56
17	2,5-(OMe)2	57	32	2,5-(OMe)2	69
18	3,4-(OMe)2	80	33	3,4-(OMe)2	59
19	2,4,5-(OMe)3	56	34	2,4,5-(OMe)3	63

^aReagents and conditions: (i) DMF-DMA (1.2 equiv), DMF, 0 °C, 1 h, 25 °C, 2 h; (ii) aldehyde (3, 1 equiv), FeCl₃ (20 mol %), dry DMF, 100 °C, 2 h; (iii) HP(O)(OEt)₂ (1.2 equiv), dry DMF, 100 °C, 2 h; (iv) NH₂NH₂·xH₂O (24–26%), DMF (or NMP), r.t., 1.5 h.

^bIsolated yields.