Table 2.

Type 1 odorants, seeking a possible counter example. (Type 1's: ‘plus’ denotes a positive response and ‘minus’ a negative response to whether the odorant is flexible.)

section	enantiomer pair	no.	flexible?	notes: a counter example?
cyclic terpenoids	(2S,4S)-2-acetyl-p-menth-6-ene and (2R,4R)	1	+	no, the (2S,4R) and (2R,4S) isomers smell different
bicyclic terpenoids	(S)- and (R)-2-methylborneol	2	−
	(1R,4S)- and (1S,4R)-fenchone	3	−
	(1R,4R)- and (1S,4S)-camphor	4	−
	(1S,4R,5R)- and (1R,4S,5S)-5-acetoxy-1,8-cineole	5	−	virtually too weak to evaluate
ionones, irones, damascones and structurally related odorants	(1′S,2S,2′R,5′S)- and (1′R,2R,2′S,5′R)-5-methyl ambercore	6	+	no, (1′R,2S,2′S,5′R) and (1′S,2R,2′R,5′S) smell different and comes with the description ‘vague’
acyclic terpenoids	(2R,3S)-, (2S,3R)-, (2S,3S)- and (2R,3R)-3-mercapto-2-methyl-pentane-1-ol	7	−	note all four are type 1; the odour description appears to be for the four isomer mixtures, but the enantiomers are differentiated by their threshold data
lactones	(4R)- and (4S)-γ-octathionolactone	8	−
	(3R)- and (3S)-butylphthalide	9	−
sesquiterpenoid	(4R,4aS,6R,8aS)- and (4S,4aR,6S,8aR)-tetrahydronootkatone	10	+	possible counter example
related odorants	(5S)- and (5R)-10-demethyl-β-vetivone	11	+	possible counter example
	(4R,5R)- and (4S,5S)-3,5-dimethyl-4-(4-methyl-pent-3-enyl)-cyclohex-2-enone	12	+	no, ‘nearly odourless’ and their isomers smell different, a partial structure of β-vetivone
steroids and sandalwood-type odorants	(1R,2′R,3′R)- and (1S,2′S,3′S)-ebanol	13	−	not very reliable; the only descriptor is ‘no sandalwood relevance’
musks	(3S)- and (3R)-3-methyl-1,4-dioxacyclopentadecan-2-one	14	−
miscellaneous	(R)- and (S)-lilial	15	−
	(4S,4aS,8aR)- and (4R,4aR,8aS)-geosmin	16	+	possible counter example
	(R)- and (S)-2-methoxy-3-[1-methylpropyl] pyrazine	17	−