Apartment investors hope to fill in another vacant lot to squeeze more profit from the Center City residential revival.

Mack-Cali Corp. says its Roseland apartment division will seek city approval to build 300 units in a new 32-story tower in the lot at 709 Chestnut St., not far from Independence Hall.

Mack-Cali is working with the Zuritsky family's Parkway Corp., which wants to use Center City's recent population boom to turn more of its surface lots into profitable new buildings. The partners hope to start work by the end of the year.

Best known as an office landlord in North Jersey, in 2013 Mack-Cali said it was selling most of its aging suburban offices around Philadelphia to focus more on apartments and mixed-use development. Center City is still an office center, but corporate demand and lease rates remain below those in other big Northeastern cities. By contrast, apartment rents are up as the neighborhood is increasingly a bedroom community for people who work in job-rich suburbs or other cities connected by road and rail.

The tower's projected cost is $118 million; the architect is HLW, New York. Rents are expected to start at $1,750 a month for a studio.

Mack-Cali chief executive Mitchell E. Hersh called the proposed 709 Chestnut tower, on a block best known for restaurants (including Jose Garces' Rosa Blanca and Stephen Starr's Jones), "a cornerstone of the burgeoning Market Street East neighborhood." The site is close to the city's historic district, Thomas Jefferson University, the new apartment projects Mack-Cali hopes to put in the former Rohm & Haas and Curtis Publishing headquarters, and the East Market and Gallery at Market East retail projects.

First step

NewSpring Capital, the $1 billion-asset, Radnor-based venture-capital group, says it has acquired 30-person, Seattle-based X5 Solutions from owner Richard Reynolds as the first section of a new national telecom company.

NewSpring, which has invested more than $1 billion in mostly East Coast-based tech companies, has hired the team of Greg Forrest and Rick Hirsh to run X5, which combines cloud-based voice, data, and Internet services into "unified communications" systems for midsized businesses, larger than the small firms served by Amazon or Comcast and smaller than giants served by Verizon, L3 Communications, or Centurylink.

Hirsh formerly headed Transcend United Technologies, a Wayne telecom firm sold to ACG Networks in 2013. In a statement, Forrest called X5 "a central first step" in NewSpring's strategy to buy regional cloud-based telecom providers "in a number of NFL-type [large] cities and create a larger geographic carrier footprint to provide expanded communications, cloud and managed services."

Insurgents

Billionaire investor Nelson Peltz has named four allies of DuPont Co. chair and CEO Ellen Kullman that he wants eliminated from the Wilmington industrial conglomerate's board of directors in a contested board election:

Alexander M. Cutler, CEO of power-equipment manufacturer Eaton and DuPont's lead director.

Robert A. Brown, president of Boston University, a former chemical engineering professor at MIT.

Lois D. Juliber, retired vice chair and chief technology officer at Colgate-Palmolive. She is a past director of Goldman Sachs, which has been advising DuPont in its defense against the attempted takeover by Peltz's Trian Fund Management. Juliber, ironically, used to represent Trian on the board of Kraft.

Lee M. Thomas, retired CEO of the lumber giant Rayonier. He also headed the Environmental Protection Agency under President Ronald Reagan.

To replace these directors on DuPont's 12-member board and boost cash flow to shareholders, Trian wants investors to vote instead for Peltz, a veteran activist investor; John H. Myers, ex-chief executive of GE Asset Management; Arthur B. Winkleblack, ex-CFO of H.J. Heinz; and Robert J. Zatta, acting CEO at Princeton-based chemical maker Rockwood Holdings Inc.