The o-nitrophenylselenoethyl functionality is a useful protected vinyl
group in porphyrins and chlorins, and its use is demonstrated in the
Vilsmeier formylation reaction which has been shown to adversely affec
t unmodified vinyl groups in tetrapyrrole systems. The X-ray crystal s
tructure for (2-o-nitrophenylselenoethyl)-3-devinylchlorin-e(6) trimet
hyl ester 14 is reported. (C) 1997, Elsevier Science Ltd.