Private equity behemoth Blackstone Group Inc. has come to terms in acquiring Allstate Life Insurance Co. from Allstate Corp. for $2.8 billion, the latest in a slew of deals between life insurance businesses and financial firms.Allstate Life Insurance Co. holds roughly 80%, or $23 billion, of Allstate’s life and entitlement reserves. The companies look forward to closing the deal in the second half of the year.Financial companies have been on the tear buying up life insurance and entitlement businesses. Last week, Sixth Street Partners revealed a deal to acquire life insurance business Talcott Resolution for $2 billion.Since the global financial crisis of 2008, private-equity, asset management and other forms of financial businesses have brought up blocks of life-insurance policies and entitlements, and even full operating units, as insurers reduced their focus and divested product lines. Ultralow interest rates have produced much of the activity, hurting profits of insurers.