I try to perform a POST from Angular to a service developed in ASP.NET Core

Hello good community I am having problems when doing a POST from Angular, I have a web service developed with ASP.NET Core 2. My post-service method is as follows:

[HttpPost]
    public async Task<IActionResult> PostTipoPago(TipoPago tipoPago)
    {

        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        _context.TipoPago.Add(tipoPago);
        await _context.SaveChangesAsync();

        return Ok(tipoPago);
    }

The TipoPago class is the following:

public class TipoPago
{
    [Key]
    public int TipoPagoId { get; set; }

    [MinLength(5), MaxLength(25), Required]
    public string Nombre { get; set; }

    [MinLength(10), MaxLength(100), Required]
    public string Detalle { get; set; }
}

Now I will show you how Angular intends to send the data so that my method of service can receive them.

addTipoPago(tipoPago: TipoPago)
{
var datos = JSON.stringify(tipoPago);
let headers = new HttpHeaders().set('Content-Type', 'application/json');
return this.http.post<TipoPago>('http://localhost:52480/api/TipoPagos', datos, { headers });
}

and the model TipoPago from Angular is as follows:

    export class TipoPago
{
  TipoPagoId: number;
  Nombre: string;
  Detalle: string;
}

and the error that I have when I execute the request is the following:

In the image you see that first I print the data that I would send to the service method, and what is happening to me is that it returns an error to me as if I was sending the data wrong, in such a way that it tells me that fields are required, as if you were receiving an empty value. I can not find what the problem could be if someone could help me would be of great help. Greetings