Given the following information, elucidate the structures of compounds A and B. Both compounds are soluble in dilute aqueous HCl, and both have the same molecular formula. The mass spectra of A and B have M⁺ 149. Other spectroscopic data for A and B are given below. Justify the structures you propose by assigning specific aspects of the data to the structures. Make sketches of the NMR spectra.

(a) The IR spectrum for compound A shows two bands in the 3300–3500 cm−1 region. The broadband proton-decoupled 13C NMR spectrum displayed the following signals (information from the DEPT 13C spectra is given in parentheses with the 13C chemical shifts).

A: ¹³CNMR: δ 140 (C), 127 (C), 125 (CH), 118 (CH), 24 (CH2), 13 (CH₃)

(b) The IR spectrum for compound B shows no bands in the 3300–3500 cm−1 region. The broadband proton-decoupled ¹³CNMR spectrum displayed the following signals: B: ¹³C NMR: δ 147 (C), 129 (CH), 115 (CH), 111 (CH), 44 (CH₂), 13(CH₃)