msal - await acquireTokenSilent

I'm implementing msal-v1 in my angular 7 application and I would like to implement my own interceptor where I get access token by calling acquireTokenSilent and then attaching the token to the http headers.

as the acquireTokenSilent is asynchronous, the token in the http headers is always empty, I need the application to wait until retrieve token and then set the headers.

First approach:

const acquireToken = async () => {
        let token = "";
        const authRequest = {
          scopes: ["user.read"],
        };
        try {
          const resp = await this.authService.acquireTokenSilent(authRequest);
          token = resp.accessToken;
        } catch (err) {
          if (err instanceof InteractionRequiredAuthError) {
            await this.authService.acquireTokenRedirect(authRequest);
          }
        }
        return token;
      };
      
      return next.handle(
        httpRequest.clone({
          setHeaders: {
            Authorization: `Bearer ${this.token}`,
          },
        })
      );

Second Approach:

const authRequest = {
            scopes: ["clientID/.default"],
          };

      var token = this.getAuthenticationToken(authRequest);

      return next.handle(
        httpRequest.clone({
          setHeaders: {
            Authorization: `Bearer ${token}`,
          },
        })
      );
    }

------------------

public getAuthenticationToken(authRequest): Promise<string> {
    
    return this.authService
      .acquireTokenSilent(authRequest)
      .then((token) => {
        console.log("Got silent access token: ", token);
        return token.accessToken;
      })
      .catch((error) => {
        console.log("Could not silently retrieve token from storage.", error);
        return this.authService
          .acquireTokenPopup(authRequest)
          .then((token) => {
            console.log("Got popup access token: ", token);
            return token.accessToken;
          })
          .catch((error) => {
            console.log("Could not retrieve token from popup.", error);
            this.authService.acquireTokenRedirect(authRequest);
            return Promise.resolve("");
          });
      });
  }

but nothing seems to work, can anyone help me to make the acquireTokenSilent as synchronous.
The reason I'm doing this approach is because I need to make the user to stay active with silent renew token in the background.