Reactivity axis

Here we describe the "clean" axis in the exported subsets of ZINC15.

Traditionally, ZINC standard subsets included: A, B, C, D, E.

ZINC "clean" subsets were just A, B, C, D.

The Clean Axis

Class	Nickname	Description	How computed
A	Anodyne	No flags of any kind set	no pattern matches whatsoever
B	Unnecessarily complex	The worst feature is the molecules are over decorated e.g. too many chlorides	complex, requires representative in A
C	Chromophore	Worst problem is a chromophore that could interfere with some asays	extended conjugated system, pattern_type = 5
D	Any PAINS	Any pains pattern not covered in E,F,G,H	pattern_type= 8 (PAINS)
E	mildly electrophilic or nucleophilic	aldhydes, thiols, michael acceptors, epoxides	pattern_type in (1,2)
F	strongly electrophilic or nucleophilic	alpha halo ketones, alkyl halides. Note includes cancer drugs.	pattern_type in (3,4)
G	unstable in buffer	typically reagents, but could be used for covalent binding. e.g. boronic acids	pattern_type = 10
H	nonsensical	idea from the PAINS papers	pattern_type = 14

other concepts mentioned, must be fit in: chelation, redox, covalent, amphiphilicity

poor derivatizability, optimizability

we never build protomers of H, G, F.

we need to classify pains by assumed mechanism

397 pains never hit any compound in zinc