Provided are compounds and salts having a structure of Formula (I) or (II): (I), and (II) wherein: both of the chiral carbon atoms denoted by “*” are both in the R configuration or both in the S configuration. Compounds and salts of Formulae (I) and (II) are useful in the preparation of enantiomerically pure amino acids. Conversion of amino acids to D-form from any of L-form, racemate or other enantiomerically impure mixtures or conversion of amino acids to L-form from any of D-form, racemate or other enantiomerically impure mixtures is disclosed.

##STR00001##

The present invention relates to novel heteroaryl-triazole compounds of the general formula (I), in which the structural elements X, Y, R.sup.1, R.sup.2, R.sup.3a, R.sup.3b, R.sup.4 and R.sup.5 have the meaning given in the description, to formulations and compositions comprising such compounds and for their use in the control of animal pests including arthropods and insects in plant protection and to their use for control of ectoparasites on animals.

##STR00001##

The disclosure provides salts of (2R,6R)-hydroxynorketamine (HNK), wherein the salt is with an organic acid chosen from malonic acid, salicylic acid, ethane sulfonic acid, glycolic acid, stearic acid, or capric acid, and their crystal forms.

The present disclosure provides a compound represented by structural formula (I): or a pharmaceutically acceptable salt thereof useful for treating a cancer.

##STR00001##

The present invention provides a method for chiral resolution of Trolox. The present disclosure relates to a method for producing a solid salt of a compound of formula I, wherein an amide-based solvent is added to a sample, which contains a compound of formula I, while being assumed to contain a compound of formula II, in the presence of an optical resolution agent:

##STR00001## Formula I: (R)-6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (hereinafter referred to R Trolox)

##STR00002## Formula II: (S)-6-hydroxy-2, 5, 7, 8-tetramethylchroman-2-carboxylic acid (hereinafter referred to S Trolox).

A method for preparing chiral synthetic nicotine includes the following steps: Step S1. condensing nicotinic acid ester and γ-butyrolactone under the action of alkaline condensate in organic solvent I to obtain the first mixture; Step S2. performing a ring-opening reaction to the first mixture obtained in Step S1 by adding an acidic substance to obtain a second mixture; Step S3. separating 4-chloro-1-(3-pyridine)-1-butanone from the second mixture obtained in Step S2, reacting with chiral tert-butyl sulfinamide to obtain chiral N-(4-chloro-1-(pyridin-3-yl)butene) -2-methylpropane-2-sulfinamide; Step S4: reacting the chiral N-(4-chloro-1-(pyridin-3-yl) butene)-2-methylpropane-2-sulfenamide with a reducing agent, and then cyclizing under the action of hydrogen halide to obtain a chiral demethylized nicotine; and Step S5: performing methylamination to the chiral demethylized nicotine to obtain a chiral nicotine.

Provided herein are compounds of Formula (I), their pharmaceutically acceptable salts, and their pharmaceutical compositions:

##STR00001##

wherein R.sup.1, R.sup.2, R.sup.3a, R.sup.3b, R.sup.4, R.sup.5, and A are defined in the present disclosure. The compounds are potent inhibitors of the main protease (M.sup.pro) of severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2), and they are useful in treating or preventing COVID-19 in a subject.

Provided herein are prodrugs comprising acyl carnitines including those of Formula (I):

##STR00001## wherein: R.sub.1 is alkyl or alkenyl; R.sub.2 is alkyl or aryl; and X.sup.− is a pharmaceutically acceptable anion.

The present invention provides a compound represented by Formula (I):

##STR00001##

wherein ring A is a substituted or unsubstituted heterocycle; ring C is a benzene ring or the like; R.sup.1 is halogen or the like; R.sup.2a and R.sup.2b are each independently hydrogen or the like; R.sup.3 is substituted or unsubstituted alkyl or the like; R.sup.4 is hydrogen or the like; and n is an integer of 1 to 3.

The present invention provides a compound represented by Formula (I):

##STR00001##

wherein ring A is a substituted or unsubstituted heterocycle; ring C is a benzene ring or the like; R.sup.1 is halogen or the like; R.sup.2a and R.sup.2b are each independently hydrogen or the like; R.sup.3 is substituted or unsubstituted alkyl or the like; R.sup.4 is hydrogen or the like; and n is an integer of 1 to 3.