Antidiabetic tricyclic compounds

A compound of structural formula I:

• or a pharmaceutically acceptable salt thereof, wherein
• A is:
• B is selected from the group consisting of:
• (1) phenyl, and
• (2) pyridyl;
• R1 is selected from the group consisting of:
• (1) halogen,
• (2) —CN,
• (3) —C1-6alkyl,
• (4) —(CH2)r—OC1-6alkyl,
• (5) —(CH2)r—C3-6cycloalkyl, and
• (6) —(CH2)r—O—(CH2)r—C3-6cycloalkyl,
• wherein each CH2, —C1-6alkyl, —OC1-6alkyl and —C3-6cycloalkyl is unsubstituted or substituted with one to four substituents selected from halogen, —C1-6alkyl and —(CH2)v—C3-6cycloalkyl;
• R2 is halogen;
• each R3 when present is independently selected from the group consisting of:
• (1) halogen,
• (2) —CN,
• (3) —C1-6alkyl, and
• (4) —(CH2)u—C3-6cycloalkyl,
• wherein each CH2, C1-6alkyl and C3-6cycloalkyl is unsubstituted or substituted with one to three substituents selected from halogen;
• R4 is selected from the group consisting of:
• (1) —O—CH2-cyclobutyl,
• (2) —O-cyclohexyl,
• (3) 2,6-diazospiro[3,3]heptan-2yl,
• (4) piperidinyl, and
• (5) phenyl,
• wherein R4 is unsubstituted or substituted with one, two, three, four or five substituents selected from R5;
• R5 is selected from the group consisting of:
• (1) —(CH2)shalogen,
• (2) —C1-6alkyl,
• (3) —(CH2)sOH,
• (4) —(CH2)sCN,
• (5) —(CH2)sSO2C1-6alkyl, and
• (6) —(CH2)sSO2—(CH2)t—C3-6cycloalkyl,
• wherein each CH2, C1-6alkyl and C3-6cycloalkyl is unsubstituted or substituted with one to three substituents selected from halogen, C1-6alkyl, and —(CH2)wOH;
• m is 0, 1, 2 or 3;
• n is 1 or 2;
• r is 0, 1,2 or 3;
• s is 0, 1, 2 or 3;
• t is 0, 1,2 or 3;
• u is 0, 1, 2 or 3;
• v is 0, 1, 2 or 3;
• and
• w is 0, 1, 2 or 3.