Amine derivative with potassium channel regulatory function, its preparation and use

An amine derivative represented by formula Ia,

• its racemes or optical isomers, its pharmaceutical acid addition salts or its amides or esters, wherein,
• (1) when R′1 is isopropyl and each of R′2 and R′3 represents methyl, R′4 may be isopropyl, n-butyl, isobutyl, t-butyl, cyclopropylmethyl, allyl, dimethylaminoethyl, diisopropyl laminoethyl;
• or
• (2) when each of R′1 and R′2 represents methyl, R′3—C—NH—R′4 may be an amine derivative represented by following formula
• I′a,
• racemes or optical isomers thereof,
• wherein each of R and R′ represents C1-5 hydrocarbyl, n represents an integer of one to eight;
• or
• when R′1 represents H2NC(CH3)2—, and each of R′2 and R′3 represents methyl, R′4 represents isopropyl;
• or when R′1 represents HOC(CH3)2—, and each of R′2 and R′3 represents methyl, R′4 represents (CH3)2CH—or (CH3)2CH(CH3)—;
• or when R′1 represents 1-hydroxylcyclohexyl, and each of R′2 and R′3 represents methyl, or R′2 and R′3 together represent —(CH2)4- or (CH2)5—, R′4 represents (CH3)2CH—;
• or when R′1 represents O2NOC(CH3)2—, and each of R′2 and R′3 represents methyl, R′4 represents (CH3)2CH—;
• or when R′1 represents
• and each of R′2 and R′3 represents methyl, or R′2 and R′3 together represent —(CH2)4—or (CH2)5—, R′4 represents (CH3)2CH—;
• or when R′1 represents
• and each of R′2 and R′3 represents methyl, R′4 represents (CH3)2CH—or (CH3)2CH(CH3)—;
• or when R′1 represents
• and each of R′2 and R′3 represents (CH2)5—, R′4 represents (CH3)2CCH(CH3)—;
• or
• (4) when R′1 represents cyclohexyl, and each of R′2 and R′3 represents methyl, R′4 may represent
• or
• when R′1 represents cyclopentyl, and R′2 and R′3 both represent —(CH2)2—, R′4 may represent
• or
• when R′1 represents isopropyl, and each of R′2 and R′3 represents
• methyl, R′4 may represent
• or
• (5) when R′1 represents isopropyl, and each of R′2 and R′3 represents methyl, R′4 may represent Val-, Trp-, lle-, Leu-, Phe-, O2N-Arg-, Pro-, Leu-Val-, Trp-Trp-Trp- or (CH3)2 CH—SO2—;
• or R4′ may represent tosyl, nicotinyl, 4-chlorobenzoyl, morphorinoacetyl, 3-thienylacetyl, or 3-indotylacetyl;
• or
• when R′1 represents cyclopropyl, and each of R′2 and R′3 represents —(CH2)2—, R′4 represents Val-;
• or
• when R′1 represents cyclohexyl, and each of R′2 and R′3 represents methyl, R′4 represents Pro-;
• or
• when R′1 represents cyclohexyl, and each of R′2 and R′3 represents —(CH2)2—, R′4 represents Pro- or nicotinyl.