I’m using the abbreviation MDR to mean Maximum Dynamic Range, to differentiate these approaches from “true” HDR.
Something I haven’t tried out in a while is Amalence’s HDRAW standalone utility. This utilizes Tone Mapping technique, allowing it to preserve the details while fitting the highest dynamic range image, taken from a single RAW photo, into the limited dynamic range of a single JPEG or any other 8-bit format.
It displays the options in popular filter examples that you just need to click on the most pleasing option (ie not shinny painting please)
Another way I have seen described to get a HDR set from a single image is to take a well exposed image and create an overexposed version and save that and then an underexposed version. Normally by moving the exposure slider by the equivalent of one f-stop. This might let you use tone mapping tools but it does not get you extra tonal range, you can find in bracketed exposures. If you want to follow this approach the new AfterShot HDR has this as its second option to create a HDR file (I don't recommend this approach)
The final approach, which I feel is the most obvious, is to use software like lightroom to stretch the tonal rendering to its maximum (well maximum acceptable amount). In this example I am using lightroom’s development module I just use the basic tonal controls controls at the top of the development tool panel. I fist try the whote balance, although in this case I feeel the as shot does reflect the warmth of the first dawn light colours well. Next I have a adjusted the exposure up a little (moving the whole histogram a littel to the right because it is so heavily biased to the left, the dark side). Next I adjust the shadows and blacks to keep the forground dark (and hide the shadow detail, for pictorial reasons). Finally I lift the highlights and the whites (there aren’t many as shown by the histogram). I lift the clarity (local contrast) and vibrance (the intensity of the deeper co0lours just a little. I do have a preset I developed ages ago called SDR+ which follows these steps but I actually prefer to do the steps manually because I can finesse the sliders in each step.
A number of software programs offers histogram stretching tools and they can produce HDR like results but they are less easily controlled than the tonal tools in packages like lightoom and AfterShot.