4‐exo Cyclizations by Template Catalysis

Small rings through large templates: A two-point binding of the substrate radicals to cationic titanocene templates is essential for the success of otherwise impossible 4-exo cyclizations (see scheme; Bn=benzyl). The cyclobutanes are obtained in high stereoselectivity and can be additionally functionalized in a straightforward manner. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.