How to get data from couch DB if my attribute start with $ symbol

Question

I have multiple documents on couch DB and I want to get data from Couch DB. my all document content below format data

{
  "_id": "\u0cc000$sysregistries\u0000Participant:Wallet\u0000",
  "_rev": "1-f35664769d9561ca4655500e2bd1244c",
  "$class": "ParticipantRegistry",
  "name": "Participant registry Wallet",
  "registryId": "model.Wallet",
  "system": false,
  "type": "Participant",
  "~version": "\u00cc00CgMBAwA="
}

I want to get databases document bases on $class property. I have tried with the below query in the mango couch DB query.

{
   "selector": {
      "$or": [
         {
            "$class": "ParticipantRegistry"
         }
      ]
   }
}

But I am getting below error Error running query. Reason: (invalid_operator) Invalid operator: $class