On the question of a corporation's fiduciary duty to convertible note holders, officers and directors generally owe duties to the corporation instead of shareholders. The officers and directors do owe duties to shareholders, though they are more context-specific and limited in scope.
A corporation’s directors owe duties of care and loyalty to shareholders, requiring them to exercise good business judgment and to show a standard of consistent care. Essentially, the standard care instructs directors to make a decision as if they are in the shoes of shareholders, instead of being a director able to profit off something that may adversely impact shareholders. If a certain decision may provide personal gain for a director, he must cede to the corporation.
The board of directors plays a role in appointing officers and upholding the fiduciary duties of shareholders, especially by delegating day-to-day decisions that impact the business's bottom line. These appointed officers act on the corporation's behalf and also owe a duty to act with care. The shareholders do not have direct control over the corporation, but they some indirect control in their meetings with directors and the board. Shareholders may also have the responsibility of forcing removal of officers or board members who breach their fiduciary duties to the shareholders.
All states have their own laws regarding how directors manage a corporation’s business and how the duty to act with care is serious and enforceable. Although questions such as who are managers for jurisdictional purposes may persist, it’s essential to ensure directors act with care.