The quartet used fake passports, claiming they were wealthy Arab brothers.
They claimed they would pay back the loan using an exclusive flat in Bayswater, west London, and provided forged documents for it.
But in reality the property had been hijacked using Land Registry documents.
The fraudsters were arrested in April 2010 after Masthaven became suspicious and stopped the deal.
Police were called in after Andrew Bloom, managing director, of Masthaven, became suspicious of the forged documentation.
Jonathan Flynn, 38, was convicted of conspiracy to commit fraud after a trial at the Old Bailey and given a four-and-a-half year prison term.
Co-conspirators Shane Martin, 51, and Ahmed Ali, 47, who pleaded guilty to their roles in the scam, each received two and a half year sentences.
A fourth man, Shakil Ahmed, 36, who donned the Arab gear along with Ali as part of the con, was given a three-year jail term in his absence after he went on the run earlier this year.
A warrant has been issued for his arrest.