How can I synthesize 2‐amino‐3‐(chlorosulfonyl)benzoic acid from toluene or benzene? I am trying to design a proper synthesis route for 2‐amino‐3‐(chlorosulfonyl)benzoic acid, though methyl 2‐amino‐3‐(chlorosulfonyl)benzoate—using an ester group in lieu of a carboxylic acid—would also be acceptable.

I am thinking a good starting material would be toluene or benzene. Here is my proposed route.

I determined the ortho-para ratio for toluene nitration from p. 816 of &quot;Organic Chemistry, 6e&quot; by Loudon &amp; Parise.

Typically, para substitution predominates over ortho substitution, but not always. For example, nitration of toluene gives twice as much o-nitrotoluene as p-nitrotoluene. This result occurs because the nitration of toluene at either the ortho or para position is so fast that it occurs on every encounter of the reagents; that is, the energy barrier for the reaction is insignificant. Hence, the product distribution corresponds simply to the relative probability of the reactions. Because the ratio of ortho and para positions is 2 : 1, the product distribution is 2 : 1.

Also, according to the same page,

The boiling points of o- and p-nitrotoluene, 220 °C and 238 °C, respectively, are sufficiently different that these isomers can be separated by careful fractional distillation.

Is there a better method? Please identify any mistakes I may have made in my synthesis and suggest improvements. Note that I install t-butyl as a blocking group in order to direct the sulfonyl chloride group ortho to the amino group.
Here is a proposed route starting from aniline.
First protect the -NH2 with t-BOC
Directed lithiation of t-BOC-aniline (sBuLi/Et2O, -75C) and quench with MeSSMe to install -SMe in the 2 position.
Directed lithiation under the same conditions quenching with Ethyl Chloroformate to install  -CO2Et in the 6 position.
Oxidise the -SMe group to sulfoxide (MCPBA, DCM)
Pummerer rearrangement of the sulfoxide (Ac2O, aq. base work up) gives the free thiol.
Oxidation of the thiol to the sulfonic acid, one example of possible conditions hydrogen peroxide with Rh catalysis
Form the sulfonyl chloride (conditions using trichlorotriazene here. Depending on your choice of conditions you can remove the -BOC group or preserve it. I think preserving it will give a flexible late stage intermediate that is reasonably easily handled. It is possible to directly form the sulfonyl chloride from the -SMe with chlorine in aq acetic acid conditions here but the conditions are harsh and risk removing the -BOC group