1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane

C184H372N30 — CID 165033839

About 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane

1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane (PubChem CID 165033839) has the molecular formula C184H372N30 and a molecular weight of 3005.21 g/mol. Its IUPAC name is 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane.

Molecular Properties

• Compound Name: 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane
• PubChem CID: 165033839
• Molecular Formula: C184H372N30
• Molecular Weight: 3005.21 g/mol
• Exact Mass: 3003.00
• IUPAC Name: 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane
• SMILES: CC(C)N1CC2CCN(C(C)C)C2C1.CC(C)N1CC2CCNC2C1.CC(C)N1CC2CN(C(C)C)C2C1.CC(C)N1CC2CN(C(C)C)C2C1.CC(C)N1CCC2C(C1)CN2C(C)C.CC(C)N1CCC2C1CCN2C(C)C.CC(C)N1CCC2C1CN2C(C)C.CC(C)N1CCC2C1CN2C(C)C.CC(C)N1CCC2CCN(C(C)C)C2C1.CC(C)N1CCC2CCN(C(C)C)C2C1.CC(C)N1CCC2CCN(C(C)C)CC2C1.CC(C)N1CCC2CN(C(C)C)CC2C1.CC(C)N1CCC2CN(C(C)C)CC2C1.CC(C)N1CCC2CN(C(C)C)CCC2C1.CC(C)N1CCC2NCC2C1.CCC.CCC
• InChI: InChI=1S/2C14H28N2.4C13H26N2.3C12H24N2.4C11H22N2.2C9H18N2.2C3H8/c1-11(2)15-7-5-14-10-16(12(3)4)8-6-13(14)9-15;1-11(2)15-7-5-13-6-8-16(12(3)4)10-14(13)9-15;2*1-10(2)14-7-5-12-6-8-15(11(3)4)13(12)9-14;2*1-10(2)14-6-5-12-7-15(11(3)4)9-13(12)8-14;1-9(2)13-7-5-12-11(13)6-8-14(12)10(3)4;1-9(2)13-6-5-12-11(7-13)8-14(12)10(3)4;1-9(2)13-7-11-5-6-14(10(3)4)12(11)8-13;2*1-8(2)12-5-10-6-13(9(3)4)11(10)7-12;2*1-8(2)12-6-5-10-11(12)7-13(10)9(3)4;1-7(2)11-4-3-9-8(6-11)5-10-9;1-7(2)11-5-8-3-4-10-9(8)6-11;2*1-3-2/h2*11-14H,5-10H2,1-4H3;4*10-13H,5-9H2,1-4H3;3*9-12H,5-8H2,1-4H3;4*8-11H,5-7H2,1-4H3;2*7-10H,3-6H2,1-2H3;2*3H2,1-2H3
• InChIKey: NBRKKWDUDQRDBI-UHFFFAOYSA-N
• XLogP: 29.15
• TPSA: 114.78 Ų
• H-Bond Donors: 2
• H-Bond Acceptors: 30
• Rotatable Bonds: 28
• Heavy Atoms: 214
• Complexity: —

Lipinski Rule of Five

3 violations

Rule	Value
MW ≤ 500	3005.21
LogP ≤ 5	29.15
H-Bond Donors ≤ 5	2
H-Bond Acceptors ≤ 10	30

Frequently Asked Questions

What is the IUPAC name of 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane?

The IUPAC name of 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane (CID 165033839) is 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane.

What is the SMILES notation for 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane?

The canonical SMILES for 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane is CC(C)N1CC2CCN(C(C)C)C2C1.CC(C)N1CC2CCNC2C1.CC(C)N1CC2CN(C(C)C)C2C1.CC(C)N1CC2CN(C(C)C)C2C1.CC(C)N1CCC2C(C1)CN2C(C)C.CC(C)N1CCC2C1CCN2C(C)C.CC(C)N1CCC2C1CN2C(C)C.CC(C)N1CCC2C1CN2C(C)C.CC(C)N1CCC2CCN(C(C)C)C2C1.CC(C)N1CCC2CCN(C(C)C)C2C1.CC(C)N1CCC2CCN(C(C)C)CC2C1.CC(C)N1CCC2CN(C(C)C)CC2C1.CC(C)N1CCC2CN(C(C)C)CC2C1.CC(C)N1CCC2CN(C(C)C)CCC2C1.CC(C)N1CCC2NCC2C1.CCC.CCC.

What is the InChIKey of 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane?

The InChIKey is NBRKKWDUDQRDBI-UHFFFAOYSA-N. The full InChI is InChI=1S/2C14H28N2.4C13H26N2.3C12H24N2.4C11H22N2.2C9H18N2.2C3H8/c1-11(2)15-7-5-14-10-16(12(3)4)8-6-13(14)9-15;1-11(2)15-7-5-13-6-8-16(12(3)4)10-14(13)9-15;2*1-10(2)14-7-5-12-6-8-15(11(3)4)13(12)9-14;2*1-10(2)14-6-5-12-7-15(11(3)4)9-13(12)8-14;1-9(2)13-7-5-12-11(13)6-8-14(12)10(3)4;1-9(2)13-6-5-12-11(7-13)8-14(12)10(3)4;1-9(2)13-7-11-5-6-14(10(3)4)12(11)8-13;2*1-8(2)12-5-10-6-13(9(3)4)11(10)7-12;2*1-8(2)12-6-5-10-11(12)7-13(10)9(3)4;1-7(2)11-4-3-9-8(6-11)5-10-9;1-7(2)11-5-8-3-4-10-9(8)6-11;2*1-3-2/h2*11-14H,5-10H2,1-4H3;4*10-13H,5-9H2,1-4H3;3*9-12H,5-8H2,1-4H3;4*8-11H,5-7H2,1-4H3;2*7-10H,3-6H2,1-2H3;2*3H2,1-2H3.

What are the key properties of 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane?

1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane has a molecular weight of 3005.21 g/mol, XLogP of 29.15, 28 rotatable bonds, 2 hydrogen bond donors, and 30 hydrogen bond acceptors.

Where does this data come from?

All data for 1,4-di(propan-2-yl)-2,3,3a,5,6,6a-hexahydropyrrolo[3,2-b]pyrrole;bis(1,6-di(propan-2-yl)-3,3a,4,5,7,7a-hexahydro-2H-pyrrolo[2,3-c]pyridine);bis(2,5-di(propan-2-yl)-3,3a,4,6,7,7a-hexahydro-1H-pyrrolo[3,4-c]pyridine);1,5-di(propan-2-yl)-2,3,3a,4,6,6a-hexahydropyrrolo[2,3-c]pyrrole;2,6-di(propan-2-yl)-1,3,4,4a,5,7,8,8a-octahydro-2,6-naphthyridine;2,7-di(propan-2-yl)-1,3,4,4a,5,6,8,8a-octahydro-2,7-naphthyridine;bis(2,6-di(propan-2-yl)-2,6-diazabicyclo[3.2.0]heptane);bis(3,6-di(propan-2-yl)-3,6-diazabicyclo[3.2.0]heptane);3,7-di(propan-2-yl)-3,7-diazabicyclo[4.2.0]octane;propane;5-propan-2-yl-2,3,3a,4,6,6a-hexahydro-1H-pyrrolo[2,3-c]pyrrole;3-propan-2-yl-3,7-diazabicyclo[4.2.0]octane is sourced from PubChem (CID 165033839), the world's largest open chemistry database maintained by the National Library of Medicine (NIH).