Table 6.

Examples of condensed dihydropyrimidone derivatives developed by Boehringer Ingelheim GmbH.

Compound	R4	R3	X	IC50 (nM)a	Reference
48 b	SO2CH3	H	CH2	4.8	[154]
49 b	H		CH2	< 1	[154]
50 b	H		CH2	< 1	[154]
51 b	SO2CH3		CH2	< 1	[154]
52 b	SO2CH3		CH2	< 1	[154]
53 b	SO2CH3		CH2	1	[155]
54 b	SO2CH3	CH2CH2OH	CH2	< 1	[155]
55 b	CONH2	CH3	CH2	1.6	[152]
56 c	H	H	NH	3.1	[156]
57 c	H		NH	1.3	[156]
58 c	H		NH	< 1	[156]
59 c		CH3	NH	< 1	[156]
60 c	CONH2	CH3	N-CH3	< 1	[156]
61 c	SO2CH3	CH3	NH	< 1	[156]

^aThe results are means of two independent experiments, each performed in duplicate (HNE enzyme assay).

^bThe absolute configuration (S) has been unambiguously assigned by X-ray structure analysis.

^cThe absolute configuration (R) has been unambiguously assigned by X-ray structure analysis.