Some [2+2] cycloaddition chemistry

Tehshik Yoon and co-workers published in Organic Letters on a [2+2] photocycloaddition.

OL paper

Nessan Kerrigan and co-workers at Oakland University have reported in JACS on a [2+2] reaction between ketenes to form beta-lactones.

JACS paper

At first look at Daniel Romo’s name I thought of Tony Romo and funny enough they’re both in Texas.  Here they report on a Mukaiyama Aldol lactonization to form beta-lactones.

JACS paper