Is it permissible to take a loan from Oman Housing Bank through the method of the bank purchasing the brother's house and then selling it to the questioner, in order to pay off a commercial bank loan with a higher interest rate, knowing that the house will remain legally owned by the questioner until the loan is repaid?

It is not permissible to use deceptive means to engage in usury (riba) or to defraud the bank. If you desire a legitimate method, the bank should genuinely purchase a property or other asset for you, and then sell it to you for a price agreed upon in the contract, even if it is more than what the bank paid for it. Once the property comes into your possession and under your guarantee, you may sell it to whomever you wish, other than the bank. It is also preferable not to sell it to the same party from whom the bank purchased it, to avoid the suspicion of 'Inah (a form of usury). This transaction is permissible and is known as Tawarruq.