Roger Sayle

"pentdec should not have been lexed as two tokens" error

1

I'm trying to understand the origins/causes of OPSIN's "should not have been lexed as two tokens" parse failures. Trying to reduce a testcase I see that: 1-(1-((2-(2,6-DIOXOPIPERIDIN-3-YL)-1,3-DIOXOISOINDOLIN-4-YL)AMINO)-3,6,9,12-TETRAOXA-PENTADECAN-15-OYL)benzene parses fine, but...

Should carbonyl oxygens be considered unsaturated?

1

The (admittedly dubious) name "4,O4-dihydro-uridine" generates the error message "hydrogen addition at locant: O4 was requested, but this atom is not unsaturated", which (pedantically) isn't entirely correct. My current work-around...

N2 locants on more amino acids: N2-methyltryptophan

1

This is an enhancement request to support N2-methyltryptophan, as currently supported by ChemDraw. As you know, for acyclic standard amino acids, N2 may be used to name the "amino" group;...

Carbohydrate locant improvements: 5a-Carba-β-D-glucopyranose

2

Hi Daniel, Is it possible (trivial) to treat locant 5a as a synonym for locant O5 in carbohydrate/saccharide nomenclature? IUPAC's 2-Carb-32.2 [https://iupac.qmul.ac.uk/2carb/34.html] recommends the name "5a-Carba-β-D-glucopyranose" which currently results in...

7-aza-2,3-indolyne

1

Today's C&N news describes synthesis of arenes (aromatic) rings containing triple bonds. The interesting nomenclature they use is 2,3-indolyne, where there is a triple bond between locants 2 and 3...