As some startups implore venture capitalists for lifelines, others are negotiating deals at eye-popping valuations without offering so much as a pitch deck. 

Airtable, which makes cloud-based software for collaboration, has spoken to investors about raising at least $50 million in a round that would value the business at between $2.5 billion and $4 billion, according to several people familiar with the company’s talks, which are informal. Airtable was valued at $1.1 billion in 2018.