Rankin v. Frebank Co. (1975) 47 Cal.App.3d 75, articulated an equitable defense to the usurpation of a corporate opportunity, concluding, among other things, that a corporate opportunity does not exist if the opportunity is not available to the corporation. (Id. at p. 88.) A corporate opportunity is not available when the party offering the opportunity is unwilling to offer it to the corporation. (Ibid.; see also 9 Witkin, Summary of Cal. Law (10th ed. 2005) Corporations, 91, pp. 864-865; 3 Fletcher, Cyclopedia Corporations (2010 rev.) 862.10, pp. 334-342.) In BT-I v. Equitable Life Assurance Society (1999) 75 Cal.App.4th 1406, the court distinguished taking advantage of a business opportunity under the partnership opportunity doctrine from the refusal-to-deal defense stated in Rankin v. Frebank Co. (1975) 47 Cal.App.3d 75. "The business opportunity doctrine allows a partner or corporate officer to take advantage of a partnership or corporate opportunity if he or she first offers it to the entity . . . ." (Id. at p. 1415.) Rankin, by contrast, "held a corporate officer was free to acquire a note without offering it to the corporation because 'there was no corporate opportunity.' " (BT-I v. Equitable Life Assurance Society, supra, at p. 1415.)