This compound is a saturated five-membered ring containing one oxygen (a tetrahydrofuran-type ring) with two chiral centers at ring carbons 2 and 5. Number the ring so that the oxygen is atom 1 and the carbon at position 2 (C2) is the chiral carbon (R configuration) bearing the larger substituent. At C2, the substituent is a single carbon that bears a hydroxyl group and is double-bonded to a nitrogen (i.e., -C(OH)=N-). This nitrogen is connected to a sulfonyl moiety (a sulfur double-bonded to two oxygens) that carries an allyl group (-CH2-CH=CH2). At the carbon at position 5 (R configuration), there is an ethyl substituent.