SAN FRANCISCO — Sidley Austin’s at it again.

About four months after venturing into Palo Alto, Sidley Austin has again plucked a corporate partner from Silicon Valley powerhouse Wilson Sonsini Goodrich & Rosati. Karen Dreyfus is joining the firm as a partner some time in April. She gave notice to Wilson Sonsini on Monday, said Thomas DeFilipps, Sidley’s Palo Alto managing partner.