Investments in Boston are starting to amount to a pretty big hill of beans.

Canada-based Oxford Properties Group, which invests in real estate on behalf of the $40 billion Ontario Municipal Employees’ Retirement System, with its joint venture partner J.P. Morgan Asset Management, is under contract to purchase two properties in Boston’s Back Bay for an estimated $1.5 billion from The Blackstone Group. The Back Bay office buildings are located at 222 Berkeley St. and 500 Boylston St., which occupy the same block and share a garage. The 758,320-square-foot 500 Boylston is valued at $867.2 million, while the Berkeley Street building is valued at $632.8 million.

Earlier this year, Oxford purchased the office located at 745 Atlantic Ave. in Boston for $114.5 million from Beacon Capital Partners. In 2014, Oxford and J.P. Morgan acquired three class A buildings in Boston and Cambridge, Mass., from Blackstone for more than $1.53 billion. And in a separate deal last year, Ox