using System.Collections.Generic;
public string Dis {get; set;}
public DType DType {get;set;}
public static void Main()
new Dat { Dis = "a", DType = DType.DatOne },
new Dat { Dis = "b", DType = DType.DisOne }
var dic = list.GroupBy(item => item.DType)
.ToDictionary(x => x.Key, x => x.Select(tag => tag.Dis).ToList());
Console.WriteLine(dic[DType.DisOne].First());